Aliased group across Trees

[DVader]

I need an alias acount or group in one tree to reference a group in another tree. Can it be done and if so what are the steps to get both trees to talk to each other.

[DVader]

Okay, a change in plans. Aperently I could do the above with federated trees, but I'd have to uninstall and reinstall Edirectory 8.5 on all the servers to set them up to be seen by other trees. This isn't practical in our enviroment.

Now I want this: If a username is not found in a context I need to do an ldap query to another tree and context to see if a user is a member of a group and then authenticate on the first tree using a default username and password. Any ideas or resources on how to acomplish this?