question regarding stems prior to mixing

Hello folks, I have a question regarding stems. If a film is going to be mixed by a mixer in 5.1, would the dialogue editor, foley, and fx person have to deliver all the combined work in a 5.1 session? I am working on dialogue editing and 2 other folks are working on foley and fx respectively. The director contacted a potential mixer which will be doing the final mix in 5.1. He requested the entire session not split in reels and in a pt 5.1 session. Is this the only way to deliver? I recall doing a super brief internship and remember the dialogue editor working in a smaller room with just a stereo setup?



if a final mixer is going to work on the 5.1, would him receiving dialogue, fx, foley etc.. in a stereo environment not be kosher?..shouldnt he just be able to open the session and pan to his hearts content?





sorry if this is a silly question, I work primarily in a 2.0 environment.









thanks!

question regarding stems prior to mixing