Fallback Auth if forwarding fails

Hi, first of all: thanks for this great software! I would like to mainly do a radius forwarding through Proxy-To-Realm functionality. This works well. But for a short period of time I need to have a fallback strategy if forwarding fails (remote RADIUS server is dead). Is there a way to match on a different entry i.e. in the users file after recognizing that the remote RADIUS server is dead? Thanks a lot for help :-)