See this link. According to this link when C connects to A it is no longer a group member of the group managed by D. Without belonging to the same group two device cannot communicate with each other.
Also if it was possible to have multiple group owners in a wifi-direct group then they could simultaneously communicate with each other along with their group members. This is optional implementation in wifi-direct according to their whitepaper. It says:
Wi-Fi Direct Device maintains membership in multiple Groups simultaneously: Optional
But in case of Android's implementation of wifi-direct, having multiple group owner is not possible. See the Andrdoid's reference. It says:
A p2p group consists of a single group owner and one or more clients.