You can create VRF groups to manage overlapping IP Ranges. Simly divide the individual networks into VRF groups. IP addresses have to be unique per VRF group, but you can have overlapping subnet ranges across VRF groups.
VRF group view page
The VRF group view page shows all of your VRF Groups.
VRF group edit page
Name: is required and must be unique among VRF groups.
Description: Free form text to enter any text.
Subnets are not displayed on the edit page.
If you make the VRF Group the default, then subnets and IP’s will be automatically assigned to this default VRF group – unless otherwise specified.