We investigate methods of co-existence between radar and communications systems. Since historically each system views the other as a source of interference, the systems are traditionally isolated spectrally or spatially in order to prevent performance degradation. By considering a cooperative radar and communications signaling scheme, we derive achievable bounds on performance for a receiver that observes communications and radar return in the same frequency allocation. These inner bounds on performance will be derived in scenarios where the radar system has to perform target parameter estimation for multiple targets. Additionally, a novel inner bound that maximizes the Fisher information for radar parameter estimation is also derived. Bounds on performance of the joint system are measured in terms of data information rate for communications and radar estimation information rate parameterization for the radar.