I talked to a couple of F/As, since I don't have access to their manuals.

The F/A storage locations are specified in their manuals. When the overhead bin is specified, the row above which they are to store their bag is listed.

Often, those overhead bins will be locking bins that are not available to passengers. I asked one about the purser's bag on the 319/320 and was told that their bags should go over row 10.

Widebodies are (almost?) all in closets, not overhead bins. 737s have the closet for the forward FA(s) and a locking overhead bin for the aft FAs.

When crewmembers DH, commute, or pass travel, their bags still look like crew bags in the overheads so not every crew bag belongs to the working crew.