Alto himself hangs up with Sheryl, which is the most developed character in the show, more than anyone, even Ranka.
He's also the one who cares for Sheryl the most ...in like every situations (he saved Sheryl in her own stage, in Galia IV, helped her stand up when she got AID..I mean Vajra disease, and in the last episodes...).
So yeah, IMO, if you cut out Alto, Sheryl is out too. And the result love triangle (Ozma-Ranka-Brera) just seems damn weird to me, I mean come on, they are brother-sisters and Ozma himself already have Cathy, don't you know?
I personally think Brera is the one who gets shoe-horned in, not Alto, if you cut him out, you won't miss anything, they could replace him with another Grace clone.