Dante, i was about to say the same thing, he has orange lacing in his wings AND the eyebrow, but those tailfeathers don't look BB hmm...
Well what i learned, one of my chicks is split to BB but she did not get ONE hourglass feather til her second molt!
this is what you should look for in the future when he either molts or his feathers come in all the way:
the bottom right and bottom middle are both feathers that show a split to Black Breasted. Lolita, the mother, is the carrier
As for the brothers in questions, they look like fawn isabels to me but i am still new to the isabel mutation so i will let Dante and Cindy take this one

Very beautiful zebbies!