Please pardon the stupid question.

I have an ex-TPE DONE3. I've already flown TPE-HKG-LHR-CDG-DFW-SFO, and its next segments are SFO-HKG-TPE (January).

For the re-issue fee, could I add in several ex-SFO intra-U.S. roundtrips? For example, could I add in an SFO-JFK-SFO and/or SFO-ORD-SFO on the ticket? It's within the same region (U.S.) and would so long as I only transit SFO three or fewer times, I can just keep adding segments, right?

Am I missing something? Thanks!