BBB emmc as mass storage to phone from otg to otg

I haven't purchased a BBB yet because I wanna be sure that it can do what I need.

I'm trying to make a phone app that will need to communicate to the beagleboard black via the phone otg port and see the BBB emmc as mass storage. Is this possible? Also, if it is, will the BBB be able to modify it's own files while the phone has it mounted?