mixing gouramis

I'm rather new to fish keeping so if this seems like a stupid and
silly question I'll apologize now... sorry!

I have recently set up a 75 gal. tank with the following fish:
3 pearl gouramis (not sexed as yet)
3 blue or three spot gouramis (not sexed as yet, either)
10 pristella or x-ray tetras
12 blackskirt tetras
4 pepper corys
4 African dwarf frogs 

It is well planted and has several rock structures for hiding and as
territory guidelines.

Now my question is, after all that pre-amble, Can I safely add a few
dwarf gouramis without either crowding the tank or having the full
size gouramis pick on the wee ones? I would love to add 3 or 4 fire
dwarf gouramis at a later date. Any and all constructive comments will
be appreciated!!

Thank you!!