I am so sorry to hear this. I know you were really fighting for this little guy, and he obviously knew how much you loved him.

I'm not sure if Tessa should be put in with the others right away or not- I will defer that to someone else.

I know you've mentioned that the gliders all play together. If they were in contact with Trevor at all, there is a good chance they have worms as well. Worms are highly contagious, and don't always show up when tested for. When you take Tessa in for testing, make sure they know about the other gliders as well, and see if it would be worthwhile to treat them all empirically.

So sorry for your loss