For what it's worth VPC ranges are allowed to overlap in GCP -- and do by default -- but then you aren't able to peer them. I kind of prefer the DO/AWS constraint.

Heh, no worries -- mostly the same deal there:

- You can do it, but it's probably not a great idea if you need to do VPC peering (or attach multiple VPCs to one VM, see next).

- Does actually work, but it does not work if the VPCs you're trying to attach to a single VM have overlapping CIDRs.

- Same deal, almost. You cannot add or remove network interfaces from an existing VM.