In this situation (if I understand correctly) they have some latitude, but it will depend on the mood of the agent you deal with. If you present yourself for the flight within a
reasonable time of its departure showing that you did in fact have a missed connection (keep your BP), the return segment can be reinstated. They may even put you on their next flight to your destination subject to a change fee, again at the agent's discretion.
More than once they have done this for me at
no charge but you should not expect this, and certainly not demand it. Throw yourself on his/her mercy
