crabbing is normal, they are scared, they are trying to chase away what is
scaring them. so they crab, like a dog barks. its a good thing, I still have
one of my 6 gliders that still crabs.
putting gliders together it is HIGHLY suggested you follow an introduction
guide and get them used to each others scent. gliders are territorial and need
time to adjust to a new glider sometimes. kind of like if someone just jumped
into your bed, most likely it would make you nervous.
I've also read a sick glider can get chased around and nipped on the tail.
you should have had a vet visit to make sure they are all healthy and no parasites.
once you get them scent trained and they live in same cage it is usually suggested
to not separate them unless they fight.