Enhancement: Make list of sortable Members List columns filterable

**Is your feature request related to a problem? Please describe.**
There isn't any way to modify the list of sortable Members List columns. 

**Describe the solution you'd like**
A filter that allows one to modify the list of sortable columns for the Members List.

**Additional context**
Such a filter would make sorting the Members List by columns such as First Name and Last Name a possibility.
