They were really more openers for the new stuff than closers of the previous, they're on the net. Betancourt wrote a prequel trilogy but it just didn't feel right, not as bad as the dune stuff but afterwards, if you're an amber fan, you'll definetly have nicer thought toward Sanderson's WoT efforts. The shorts afterward are first-person from Merlin, Luke, and Corwin, IIRC 'Blue Horse, Dancing Mountain' is the first chronologically, doesn't matter much, and wherever you dfind one you'll find the others too.