New IEEE Standard - Active. A recommended practice for applying the Distributed Simulation Engineering and Execution Process (DSEEP) to the development and execution of distributed simulation environments that include more than one distributed simulation architecture is described. The distributed simulation architectures to which the recommended practice applies include Distributed Interactive Simulation (DIS), High Level Architecture (HLA), and Test and Training Enabling Architecture (TENA). The DSEEP Multi-Architecture Overlay (DMAO) identifies and describes multi-architecture issues and provides recommended actions for simulation environment developers faced with those issues. The DMAO also augments the DSEEP lists of inputs, recommended tasks, and outcomes with additional inputs, recommended tasks, and outcomes that apply to multi-architecture simulation environments. This document is an overlay to the DSEEP, which is a separate recommended practice.