If you want your two virtual machines to be able to communicate with each other all you need to do is configure a Virtual switch in through HyperV Manager, I suggest either a Private virtual switch or an Internal virtual switch. then connect the network adaptor of each VM to the same switch. As long as IP settings match i.e they are on the same network with their own host address, the two VMs should be able to communicate with each other. I use this configuration all the time for testing and development.
If the two VMs cant communicate with each other then there is probably something wrong with the OS configuration in the VMs themselves.