Katy,
Do the 3 users have their own workstations back at the main office? If so, then you could be logging on remotely to "Katy's computer", and another user to "Dan's computer" and so on, just like the main office. LogMeIn is a remote control program, so it acts like a physical person sitting in front of that one computer only being remotely controlled. You can't have two people using one computer at the same time, either physically or remotely.
There are other solutions like having a DNS server that get beyond my level almost instantly, and ratchet up the cost significantly. If you really have 3 or more providers, however, you may hit economies of scale that would make this worthwhile. Others here will be able to comment better than I.
The synch function should probably be used as an emergency use item, or for updating the AC iPhone app. It is not stable.
