Sorry to drag this topic back alive but I have a successful multi species colony. Both are Polyrhachis (Cyrtomyrma) and have been raised together since solo queens. I haven't ID'd them to species but I can confirm they're different (one has spikes on the first abdominal segment while the other doesn't, and one has a much longer petiole and connecty bits than the other). Any thoughts?
No, I think a successful multi species colony is a justified reason to bring it back. We would love to se images of the colony if you have one!