Can I add my freelance designer to my wpmudev dashboard?

I am brand new to wpmuDev, and also to using WordPress. I have hired a designer to develop a site for me, but I purchased the wpmuDev membership so that I could have the support and education in learning what seems overwhelming to me.

I would like to have this freelancer have access to my wpmuDev account so that he can load in the plug-ins and such.

I'd rather he have his own sign in access. However, if sometime later down the road he is no longer my designer and I want to cancel his access, it means all of his work also goes away, I guess that would not be a valuable situation.

So, my question is:
How do I go about setting up access to my wpmuDev account for my designer to use? If it is a separate log in, will that log in cancel his work if it is ever cancelled?

Thank you for the help!

-Wendy