Heh whoops! I just looked up some good sounding names with names. Celeste came up as heavenly so I thought hat be good for a Pegasus xD I can change it if you want.

No worries, they don't do too much. 

Zahir currently really is only Zidar's eyes and doesn't have any other ability. And Celeste currently is mostly just a minor healer with a little bit of attack power (but not much). Later on, more attack base summons may be acquired and Zahir and Celeste could get better abilities.

No worries on sharing the tree, since Zidar's only abilities is summoning those two and defending. That's it. XD