Just saw our CL squad.
Emre Can will have to be included instead of Demiral. That way we add someone to take Khedira's place in midfield and we also add someone who could serve as a 4th choice CB in case of emergency. That would leave us one more open spot, because I assume Khedira won't be included in the list. Chiellini could fill that spot.
In any case, we have only 21 players+Pinsoglio that we can include in the A list for CL. As things stand, Chiellini and Can for Demiral and Khedira. But if we buy anyone else, we'll either have to exclude someone from the CL list, or this new player can be eligible only for serie A matches.