Yes you can. But you need to go to your control panel > I can't remember, I think it's admin > sharing or something like that. You can create a new folder & make any users of your choice have equal access to it. So yes, it can become a common folder. (btw I have prevously listed the steps on the forum so perhaps you could search for it.)

Not sure why you'd have several accounts all belonging to yourself. I have a few purely for experimental reasons when running LW.