I see that other post had a VBA snippet for taking files from another location and automatically attaching them to the geodatabase, but didn't see anything about dividing one.
Some of the post wanted to carry the link as the attachment, then have the files elsewhere. Seems like this would just be having a path in a field and hyperlinked to the file, but not with realted 1:many data.
In any case, are you just running out of server space, or is your GDB getting too large for performance?
When I have "huge" datasets, and the GDB gets too large, I split them.
Not sure what your workflow is, but could you have most your data in one FGDB, then have the editing feature and it's attachments in a separate FGDB?
R_