diff --git a/manual/ele-types.tex b/manual/ele-types.tex
index dda69c8..820a247 100644
--- a/manual/ele-types.tex
+++ b/manual/ele-types.tex
@@ -361,7 +361,7 @@ \section{Fork}
 Element parameter groups associated with this element type are:
 \TOPrule
 \begin{example}
-  FloorParams -> Floor floor position and orientation. \sref{s:orientation.g} 
+  FloorParams         -> Floor floor position and orientation. \sref{s:orientation.g} 
   LengthParams        -> Length and s-position parameters. \sref{s:length.g} 
   DescriptionParams   -> Element descriptive strings. \sref{s:descrip.g} 
   TrackingParams      -> Default tracking settings. \sref{s:tracking.g} 
@@ -381,12 +381,13 @@ \section{Fork}
 
 The components of this group are:
 \begin{example}
-  to_line::Union{BeamLine,Branch}   - Beam line to fork to
-  to_ele::Union{String,Ele}         - Element forked to.
+  to_line::Union{BeamLine,Nothing}  - Beam line to fork to. Default: nothing.
+  to_ele::Union{String,Ele,Nothing} - Element forked to. Default: nothing.
   direction::Int                    - Longitudinal Direction of injected beam.
 \end{example}
 
-
+If \vn{to_line} is set to a \vn{BeamLine} -> New branch
+Otherwise the fork is to an existing lattice element.
 
 
 
diff --git a/src/bookkeeper.jl b/src/bookkeeper.jl
index 64a65df..96129f4 100644
--- a/src/bookkeeper.jl
+++ b/src/bookkeeper.jl
@@ -591,6 +591,7 @@ function ele_paramgroup_bookkeeper!(ele::Ele, group::Type{ForkParams},
                                               changed::ChangedLedger, previous_ele::Ele)
   fg = ele.ForkParams
   rg = ele.ReferenceParams
+  clear_changed!(ele, ForkParams)
 
   to_ele = fg.to_ele
   to_ele.ix_ele != 1 && return
@@ -608,8 +609,6 @@ function ele_paramgroup_bookkeeper!(ele::Ele, group::Type{ForkParams},
   to_ele.pc_ref      = rg.pc_ref
 
   set_branch_min_max_changed!(to_ele.branch, 1)
-  clear_changed!(ele, ForkParams)
-
   return
 end
 
@@ -955,35 +954,50 @@ Adds the `Branch` that is forked to to the lattice.
 """ fork_bookkeeper
 
 function fork_bookkeeper(fork::Ele)
-  # No to_line means fork to existing element.
-  if isnothing(fork.to_line)
-    if typeof(fork.to_ele) != Ele; error("Since to_line is not specified for fork $(fork.name),\n" *
-                                         "to_ele must be an actual element in a lattice."); end
-    lat = lattice(ele)
-    if isnothing(lat); error("Since to_line is not specified for fork $(fork.name),\n" *
-                             "to_ele must be in a lattice and not external."); end
-
-  # Fork to new branch
-  else
-    lat = fork.branch.lat
+  isnothing(fork.to_ele) && isnothing(fork.to_line) && 
+                                error("Neither to_ele nor to_line set for Fork element $(fork.name)")
+  isnothing(fork.to_ele) && typeof(fork.to_line) == Lattice && 
+                                error("to_ele not set for fork element $(fork.name)")
+
+  lat = fork.branch.lat
+
+  # If to_line is a BeamLine then forking to a new branch
+  if typeof(fork.to_line) == BeamLine 
+    typeof(fork.to_ele) == Ele && !isnothing(lattice(fork.to_ele)) && error(
+        "Confusion: to_line is a BeamLine and to_ele is associated with a Lattice for fork element $(fork.name).")
+
     to_branch = new_tracking_branch!(lat, fork.to_line)
-    if typeof(fork.to_ele) == Ele; error(
-      "Since to_line is specified, to_ele must be something (String, Regex) that can be used with \n" *
-      "the `find` function to locate the element in the new branch and cannot be an existing element."); end
 
-    if fork.to_ele == ""
+    if isnothing(fork.to_ele)
       fork.to_ele = to_branch[1]
     else
-      to_ele = eles_search(lat, fork.to_ele)
-      if length(to_ele) == 0; error("to_ele ($(fork.to_ele)) not found in new branch for fork $(fork.name)."); end
-      if length(to_ele) > 1; error("Multiple elements matched to to_ele ($(fork.to_ele)) for fork $(fork.name)."); end
-      fork.to_ele = to_ele[1]
-    end
+      if typeof(fork.to_ele) == Ele
+        name = fork.to_ele.name
+      else  # String
+        name = fork.to_ele
+      end
 
-    to_ele = fork.to_ele
-    if to_ele.ix_ele == 1
-      to_ele.from_forks = [fork]
+      to_eles = eles_search(to_branch, name)
+      if length(to_eles) == 0; error("to_ele $name not found in new branch for fork $(fork.name)."); end
+      if length(to_eles) > 1; error("Multiple elements matched to to_ele $name) for fork $(fork.name)."); end
+      fork.to_ele = to_eles[1]
     end
+
+  # to_line is nothing means fork to existing element.
+  elseif typeof(fork.to_ele) == String
+    to_eles = eles_search(lat, fork.to_ele)
+    if length(to_eles) == 0; error("to_ele $name not found in new branch for fork $(fork.name)."); end
+    if length(to_eles) > 1; error("Multiple elements matched to to_ele $name) for fork $(fork.name)."); end
+    fork.to_ele = to_eles[1]
+  end
+
+  # 
+
+  to_ele = fork.to_ele
+  if haskey(to_ele.pdict, :from_forks)
+    push!(to_ele.pdict[:from_forks], fork)
+  else
+    to_ele.pdict[:from_forks] = Vector{Ele}([fork])
   end
 
   return
diff --git a/src/lat_construction.jl b/src/lat_construction.jl
index e1c0747..0d15e13 100644
--- a/src/lat_construction.jl
+++ b/src/lat_construction.jl
@@ -242,14 +242,17 @@ function new_tracking_branch!(lat::Lattice, bline::BeamLine)
   for outer ib in reverse(1:length(lat.branch))
     if lat.branch[ib].type == TrackingBranch; break; end
   end
+  ib += 1
 
-  insert!(lat.branch, ib+1, Branch(name = bline.pdict[:name], lat = lat, 
+  insert!(lat.branch, ib, Branch(name = bline.pdict[:name], lat = lat, 
                               pdict = Dict{Symbol,Any}(:geometry => bline.pdict[:geometry])))
-  branch = lat.branch[ib+1]
+  for ix in ib:length(lat.branch)
+    lat.branch[ix].pdict[:ix_branch] = ix
+  end
 
-  branch.pdict[:ix_branch] = length(lat.branch)
+  branch = lat.branch[ib]
   branch.pdict[:type] = TrackingBranch
-  if branch.name == ""; branch.name = "B" * string(length(lat.branch)); end
+  if branch.name == ""; branch.name = "B" * string(ib); end
   info = LatticeConstructionInfo([], bline.pdict[:orientation], 0)
 
   if haskey(bline.pdict, :species_ref); branch.ele[1].species_ref = bline.pdict[:species_ref]; end
@@ -262,7 +265,7 @@ function new_tracking_branch!(lat::Lattice, bline::BeamLine)
     add_beamline_ele_to_branch!(branch, BeamLineItem(bline.pdict[:end_ele]))
   else
     @ele end_ele = Marker()
-    end_ele.pdict[:name] = "end$(length(lat.branch))"
+    end_ele.pdict[:name] = "end$(ib)"
     add_beamline_ele_to_branch!(branch, BeamLineItem(end_ele))
   end
 
diff --git a/src/query.jl b/src/query.jl
index c505395..0ec9122 100644
--- a/src/query.jl
+++ b/src/query.jl
@@ -96,17 +96,19 @@ function ele_geometry(ele::Ele)
 end
 
 #---------------------------------------------------------------------------------------------------
-# is_null(ele), is_null(branch)
+# is_null(ele), is_null(branch), is_null(species
 
 """
     is_null(ele::Ele)
     is_null(branch::Branch
+    is_null(species::Species)
 
-Test if argument is either of the `NULL_ELE` or `NULL_BRANCH` constants.
+Test if argument is either of the `NULL_ELE`, `NULL_BRANCH`, or null species. constants.
 """ is_null
 
-is_null(ele::Ele) = return (ele.name == "NULL_ELE")
-is_null(branch::Branch) = return (branch.name == "NULL_BRANCH")
+is_null(ele::Ele) = (ele.name == "NULL_ELE")
+is_null(branch::Branch) = (branch.name == "NULL_BRANCH")
+is_null(species::Species) = (species == Species())
 
 #---------------------------------------------------------------------------------------------------
 # s_inbounds
diff --git a/src/struct.jl b/src/struct.jl
index 1c6345f..188c932 100644
--- a/src/struct.jl
+++ b/src/struct.jl
@@ -732,17 +732,17 @@ end
 Fork element parameters.
 
 ## Fields
-• `to_line::Union{BeamLine,Nothing}`  - Beam line to fork to. \\
-• `to_ele::Union{String,Ele}`         - On input: Element ID or element itself. \\
-• `direction::Int`                    - Longitudinal Direction of injected beam. \\
-• `propagate_reference::Bool`         - Propagate reference species and energy? \\
+• `to_line::Union{BeamLine,Nothing}`    - Beam line to fork to. \\
+• `to_ele::Union{String,Ele,Nothing}`   - On input: Element ID or element itself. \\
+• `direction::Int`                      - Longitudinal Direction of injected beam. \\
+• `propagate_reference::Bool`           - Propagate reference species and energy? \\
 
 
 """ ForkParams
 
 @kwdef mutable struct ForkParams <: EleParams
   to_line::Union{BeamLine,Nothing} = nothing
-  to_ele::Union{String,Ele} = ""
+  to_ele::Union{String,Ele,Nothing} = nothing
   direction::Int = +1
   propagate_reference::Bool = true
 end
diff --git a/src/utilities.jl b/src/utilities.jl
index 7e9d653..abaadf4 100644
--- a/src/utilities.jl
+++ b/src/utilities.jl
@@ -7,11 +7,8 @@
 
 """
     lat_sanity_check(lat::Lattice)
-    Internal: lat_sanity_check(lat::Lattice, base_ele::Ele, pointed_ele::Ele, err_string::String)
 
 Does some self consistency checks on a lattice and throws an error if there is a problem.
-
-The internal version of `lat_sanity_check` is called by the public version and is not usable otherwise.
 """ lat_sanity_check
 
 function lat_sanity_check(lat::Lattice)
@@ -40,43 +37,43 @@ function lat_sanity_check(lat::Lattice)
       end
       
       if haskey(pdict, :girder)
-        lat_sanity_check(lat, ele, pdict[:girder], "girder")
+        check_pointed(lat, ele, pdict[:girder], "girder")
       end
       
       if haskey(pdict, :multipass_lord)
-        lat_sanity_check(lat, ele, pdict[:multipass_lord], "multipass lord")
+        check_pointed(lat, ele, pdict[:multipass_lord], "multipass lord")
       end
 
       if haskey(pdict, :ForkParams)
-        lat_sanity_check(lat, ele, pdict[:ForkParams].to_ele, "a forked-to element")
+        check_pointed(lat, ele, pdict[:ForkParams].to_ele, "a forked-to element")
         if ele.L != 0; error("A Fork element may not have a non-zero length: $(ele_name(ele))"); end
       end
 
       if haskey(pdict, :OriginEleParams)
-        lat_sanity_check(lat, ele, pdict[:OriginEleParams].origin_ele, "the element's origin element")
+        check_pointed(lat, ele, pdict[:OriginEleParams].origin_ele, "the element's origin element")
       end
 
       if haskey(pdict, :super_lords)
         for lord in pdict[:super_lords]
-          lat_sanity_check(lat, ele, lord, "super lord")
+          check_pointed(lat, ele, lord, "super lord")
         end
       end
 
       if haskey(pdict, :slaves)
         for slave in pdict[:slaves]
-          lat_sanity_check(lat, ele, slave, "slave")
+          check_pointed(lat, ele, slave, "slave")
         end
       end
 
       if haskey(pdict, :from_forks)
         for fork in pdict[:from_forks]
-          lat_sanity_check(lat, ele, fork, "a fork that is forking to this element")
+          check_pointed(lat, ele, fork, "a fork that is forking to this element")
         end
       end
 
       if haskey(pdict, :GirderParams)
         for slave in pdict[:GirderParams].supported
-          lat_sanity_check(lat, ele, slave, "supported element")
+          check_pointed(lat, ele, slave, "supported element")
         end
       end
 
@@ -85,12 +82,15 @@ function lat_sanity_check(lat::Lattice)
 end
 
 #-------------------
-# Internal lat_sanity_check method
+# Internal check_pointed method
 
-function lat_sanity_check(lat::Lattice, base_ele::Ele, pointed_ele::Ele, err_string::String)
+"""
+    Internal: check_pointed(lat::Lattice, base_ele::Ele, pointed_ele::Ele, err_string::String)
+"""
+function check_pointed(lat::Lattice, base_ele::Ele, pointed_ele::Ele, err_string::String)
   pele = lat.branch[pointed_ele.branch.ix_branch].ele[pointed_ele.ix_ele]
   if !(pointed_ele === pele)
-    error("Element $(ele_name(ele)) has a $err_string pointer to $(ele_name(pele)) but this\n" *
+    error("Element $(ele_name(base_ele)) has a $err_string pointer to $(ele_name(pele)) but this\n" *
           " pointed to element is in a different lattice!!!")
   end
 end
diff --git a/test/fork_test.jl b/test/fork_test.jl
index 7a3efcb..c0e4378 100644
--- a/test/fork_test.jl
+++ b/test/fork_test.jl
@@ -1,30 +1,42 @@
 using AcceleratorLattice, Test
 
 @ele begin1 = BeginningEle(species_ref = Species("electron"), pc_ref = 1e6)
-@ele begin2 = BeginningEle()
-
+@ele begin2 = BeginningEle(species_ref = Species("proton"), pc_ref = 1e7)
+@ele begin3 = BeginningEle(species_ref = Species("photon"), E_tot_ref = 1e3)
+@ele mk1 = Marker()
 @ele bend1 = Bend(g = 1, angle = pi/2, Kn2L = 0.1, Bs3 = 0.2, En4 = 0.3, Es5L = 0.4)
+@ele dft = Drift(L = 2)
 bend2 = copy(bend1)
 bend2.name = "bend2"
 bend2.tilt_ref = pi/2
 
 @ele fork1 = Fork()
+@ele fork2 = Fork(propagate_reference = false)
+@ele fork3 = Fork(to_ele = "mk1")
 
-line1 = BeamLine([begin1, bend1, fork1])
+line1 = BeamLine([begin1, bend1, fork1, mk1])
 line2 = BeamLine([begin2, bend2])
+line3 = BeamLine([begin3, dft, fork3])
+
 fork1.to_line = line2
+fork2.to_line = line3
 
 lat = Lattice([line1])
 
+superimpose!(fork2, lat["bend2"], offset = 0.2)
+
 b1 = lat.branch[1]
 b2 = lat.branch[2]
 
+
+
 @testset "bend_bookkeeping" begin
 
 
 end
 
 # test fork superimpose
+# test fork with multipass
 # test fork to existing branch.
 # make sure finite L throws error.
 # check that forked to branch inherits reference energy from fork.