I personally have a main account and a mule account. Crystal here is my main character and my mule account has about half a dozen mules on it (I'm a hoarder with all 50s gathering and crafting on Crystal so that takes up a lot of room XD). I made an FC and put all of my mules into it. Crystal wasn't a member but at least my mules can access the shared FC bank. That way I can collect logs and cloth and whatever on a single character when usually it'd be on 3, then mail/trade them all to Crystal at once, or mail all sorts of things from Crystal to one mule instead of to several. Certainly not ideal but better than nothing.