point-to-multipoint can certainly be a physical implementation. Probably the easiest way to do it is to set up one router as a frame relay switch. Then set up three routers as frame relay hub and spoke. On the hub router map the Frame Relay DLCIs to the physical interface, or if you want you can create a point to multipoint subinterface and map the DLCIs to it. Then you have got a genuine point-to-multipoint implementation.
HTH
Rick