Training and Doctrine Command (TRADOC) is executing its plan to replace its primary entity driver in the Battle Lab Collaborative Simulation Environment (BLCSE). Replacing the existing multipurpose OneSAF Testbed Baseline (OTB) functionalities with OneSAF Objective System (OOS) will transition Army experimentation in the Advanced Concepts and Requirements domain to a fully capable environment for the study and testing of Future Combat Systems (FCS) capabilities. Because BLCSE maintains an aggressive analytical experimentation schedule, the transition from OTB to OOS must be completed in a short timeframe while preventing loss of functionality for remaining BLCSE federate applications. This paper discusses the technical issues associated with BLCSE's SAF replacement process, ranging from entity driver replacement to simulation message protocol adaptation. The paper specifically describes near-term activities associated with identification and resolution of interoperability issues and functionality gaps within a large-scale, highly-distributed simulation environment. In addition, the paper discusses potential enhancements to the BLCSE environment made possible by the integration of OOS, including behavior and modeling flexibility, varying entity fidelity and the introduction of OOS-based servers and tools.