No worries, took me a little while to find it myself!
After discussing internally, we concluded that reassigning MAAS-deployed machines to new subnets isn’t a use case we currently support, nor is it one we’re currently investigating.
We’ve had a few users request it, so we can see there’s at least some desire for the feature. If anyone in the community can make it work, we’d happily learn from them.
There is a potential workaround, but it’s unsupported and potentially arduous:
Manually disconnect the machines from MAAS after deploying them, and configure the networking separately afterwards as per requirement. In essesnce, using MAAS for initial provisioning and sanity testing. Rebuild the machines with standard installers once they’ve been released and configured.
My apologies for not having anything more concrete, but if you get anywhere with this we’d be happy to hear more! Getting extra information on real world implementations is always a great help for improving MAAS.
I would definitely reccomend checking if the wider community has done anything similar to this, or has any better ideas than already put forward.