Required software development freelancer for Need Remote Desktop or VPN Solution job

I work with virtual assistants and need better collaboration for some files than Dropbox shared folders can provide.

I currently maintain a PC that my virtual assistants can login to using Logmein. The problem is only one can at a time, but I don't want to have remote PCs as it isn't that often I need more than one person with access at the same time.

Can my remote PC be setup for multiple people to login as different users and work at the same time? I realize the computer needs enough RAM and CPU power for this.

Another solution would be can drives be remotely networked through a VPN but share a drive so it was like we were on the same physical network. I would like to be able to run network versions of software like QuickBooks so multiple people could work on the software and files at the same time.

I am open to ideas. In reality, this is for like 3-4 people.

Skills & Expertise Required

software development