IEEE Std 2846-2022 defines, for a set of initial scenarios, a minimum set of assumptions to be considered by safety-related models to represent the reasonably foreseeable behavior of other road users (ORUs). This recommended practice provides guidelines for using these assumptions in safety-related models during development, testing, and deployment of Automated Driving Systems (ADS). Specifically, it covers: (i) Approaches to identify values for the applicable IEEE Std 2846-2022 assumptions given the scenario context, such as scenario type, roadway information, and safety-relevant objects. (ii) Approaches for identifying reasonably foreseeable values for the assumptions given the scenario context (from (i) above) and for updating the assumptions across the temporal evolution of a scenario; and (iii) Approaches to validate the selection of assumptions in (ii) through an analysis of the output of the safety-related model, considering different kinds of performance targets of interest. Compliance with this recommended practice does not guarantee the safety of the overall system. New IEEE Standard - Active - Draft. This recommended practice provides guidelines for applying the assumptions defined in IEEE 2846:2022 in safety-related models during the development, testing, and deployment of Automated Driving Systems (ADS). It specifically covers approaches to identify values for the applicable IEEE 2846:2022 assumptions given the scenario context; approaches for identifying reasonably foreseeable values for these assumptions given the scenario context and for updating these assumptions across the temporal evolution of a scenario; and approaches to validate the selection of assumptions through an analysis of the output of the safety-related model, considering different kinds of performance objectives of interest.