Oh so basically I want to add the Win 7 machine to the Win server domain but they need to be able to see each other on the virtual network, which I'm not sure how to do.
There are a lot of ways to achieve the particular configuration. I would suggest you to take a look at the networking guides/topics in the user manual. This will give you more overview of the virtual networking options available.
After going through that try setting up the virtual network and let us know here if you face any issues.
it also depends on what way you have your vNICs setup currently. The easiest way is to either set each Network Adapter up in Bridged mode or setting them up with a custom VMnet adapter (make sure both servers are on the same VMnet). They should then be able to communicate with each other if you setup their IP's, Subnet, and Default Gateways.