Since WindowsVirtualDesktop (#WVD) currently still requires you to join the Session Hosts to AD (and sync accounts between AD and AAD), this article helps explain how to deal with multiple forests. via @brinkhoff_c

Source: https://docs.microsoft.com/en-us/azure/architecture/example-scenario/wvd/multi-forest?_lrsc=e5db49b6-7e8d-4d9b-b580-ce8796d718e3