I have had this issue for nearly every custom follower I download (except mods like Dralora of Vivec, Alynna and "bunch of npcs" mods) and it involves knowing how to change custom follower bodies to cbbe. When they come with their own custom body like some mods just as the "Nell brat" follower mod on this site in particular or the Bjinn mods for vanilla npcs (which use UNP) I can't adjust anything to them.   They don't get affected by my "breast and size scaling" mod either (www.nexusmods.com/