in fact, relay nodes are not implemented in the Vienna LTE-A downlink system level Simulator. Remote Radio Heads are a different concept, where several active transceivers are connected to a BS via fiber, not over the air-interface as it is the case for relays. Therefore also simultaneously transmission is assumed from all combined antennas of macro BS and all connected RRHs. You find an example for this in the launcher files in LTE_sim_main_launcher_demo_RRH.
Regarding your question about cell range extension: the sector assignment is done in LTE_common_calculate_cell_capacity. If you adapt this to not be based on the SINR, but on the received power and add a fixed value on, e.g., the received power from femto-cells, this should solve your problem.