POTD save status after character transfer?

I'm new to the forums so apologies if this has been asked before or if it's in the wrong place!

My friends and I had a save file that was above floor 100, and now one of our party members has transferred off of our data center. My question is, if they transfer back, can we resume that file or is it permanently broken? I've asked in-game using the support desk and was told to look at the Active Help page (there was nothing about deep dungeons in there unless I am completely blind) or make a post about it here. Google tells me that the file can't be used if one party member is unavailable and I get that, but no mention of if the unavailable player can return.

Any insight is appreciated. I mainly just want to know if I should keep that save file there or if it's just a waste of space. =p