Originally Posted by wldtrvlr

That would be a nested ticket and as long as it was not booked to violate a fare rule on A-C than there is nothing wrong with it. As long as you actually have a stopover in city B not much can be said. However, if your stop is less than 4 hours and the airline views it as a connecting flight than it could cause problems if A-C cost more than A-B & B-C.