I have also been looking at this interesting collection of photographs. Photos number 3 and 4 are well known views: the woman and baby is a cdv version of #38 in Hamilton & Hoyt's stereographic series; the man with the flag and rifle is Green Cloud from Hamilton's series, the number is partially obscured in the example I have seen.
As to the remaining portraits with the curtain backdrop, they are all new to me. I have not seen any Cross photos with this type of backdrop. So like all of you, I am still searching for who this photographer might be!
I´ve recently seen this previously unidentified portrait by an unknown photographer ID´d as Frank Lock aka Lock of Hair. He was an Carlisle student and the school records there say he was a son of George Sword: