As I already explained, this is not a use case supported by Netbox and you'd have to write your own tool to do this. Alternatively, you can find some other software which meets your needs better.
The core Netbox data model in this area is:
,--------------<
Site ---< Rack ----< Device ----------< Interface ------<
IPAddress
Cluster -----------< VirtualMachine --< VMInterface ----<
Therefore if you move am IP Addresses from one instance to another, you'll have to carry forward the references to the appropriate Interface/VMInterface objects, which means mapping the Interface ID or VMInterface ID on one Netbox instance to that on another Netbox instance.
Netbox doesn't have any UUID which would allow you to keep the same interface ID on both instances. You can sometimes match using a combination of device/VM name and interface name, but beware that:
- devices can be unnamed
- even when set, device names are not globally unique (they are unique for a given site+tenant)
- VM names are not globally unique (they are unique for a given cluster+tenant)
Hence the tuple of (site name, tenant name, device name, interface name) will often identify a device interface, but not when the device is unnamed.