1. Add their user name to your VM.
(a) my computer--Manage
(b) groups--users--property
(c) add
(d) check the dormin name first, then enter your co-workers user name.
2. Add their user name to remote
(a) Contro Panel--System--Remote
(b) click select remote users
(c) check domin first, then add user name, then check names
Now, you can tell your co-workers to try.