The Gravity Forms team says they have never worked with URE but they have hooks that could be used for what we want to do if we know the actions to perform.

Has the list of hooks.

They believe the user updated one is what we need. https://www.gravityhelp.com/documentation/article/gform_user_updated/

Can you tell me what the PHP code would need to do in order for me to add a checkbox field for adding secondary roles?