Thank you everyone
They are a special group, and are all such amazingly sweet buns.
I think the most difficult thing was just getting them interacting with each other... I think it is easier with a pair as they have no one else to interact with, but with an existing pair it is easier for them to ignore the new one. Luna and Arnold were okay with Ludo from the start, a few minor scuffles that were mainly caused by
Ludo's slightly irritating behaviour, but apart from that they took to him pretty well. Ludo was very into them and would snuggle up to them, and while they allowed him, they didn't initiate it themselves. They are getting far, far better in that respect now, and spend a lot of time cuddling together.