Ability to set ip address when joining another ipvlan network

[z0nderling]

** Environment description **
Multiple ipvlan networks with multiple subnets and specific gateways for ipv4/ipv6 (>12) are defined and running.
The ability to create containers with a specific ipv4/ipv6 address and join a network is done over "add container".

feature request
In my case, users should have the ability to let a running container join another network with a specific ipv4/ipv6 ip! Since every ipvlan network has multiple subnets defined , the container should join the right subnet with the gateway defined for the subnet because of reasons.

Currently it is possible to join another network, but the ip assignment is some kind of random..which leads to the problem that there are routing problems and you have to change the ip and default gateway manually

Describe the solution you'd like
A simple solution would be to add 2 more text boxes for ipv4/ipv6 addresses in addition to the "Join Network" button.