The AA divert IOM is not impacted by transit AA subscribers in the divert parent. The ISA host IOM egress datapath functions to convert the parent SAP into transit AA subscribers that are then handled by the ISA consistent with all other AA subscriber features. The ISA itself treats all AA subscribers equally regardless of whether the AA subscriber is from ESM, from DSM, from an SAP, or from a transit subscriber in a parent SAP or spoke.
Prefix transit subs can only be created on IOM3-xp as host IOM, or with MS-ISM as host for ISA2. Asymmetry removal requires IOM3-xp or MS-ISM as host and IOM3-xp or newer (IMM) as divert IOM.