"Kind of a stupid question, but since she can't take any of Gril's headmorphs at all, wouldn't a better solution to be to just hide aiko's head, and hide girl's body, and then use that combo?"

???

Please read the first page of this thread and the ReadMe, Garee.

Of course GIRL 3 can take all of the "normal" Girls headmorphs.
(And any 3rd party morphs for the Girl, too)

Same for the body, which can use all of AIKO´s morphs.

You first have to transfer the morphs and channels back into the GIRL 3 cr2 with MorphManager of course.

If I left all morphs in place, the download would be almost 50mb big instead of just 7mb.

Stahlratte