Originally Posted by
Often1
Busy agents tend to skip steps which they should not. That is between BA and them (or in the case of interline, some other carrier). Nonetheless, the anecdotal evidence that a practice sometimes works is not something I would ever rely on or argue about.
If you are charged, don't argue. If the issue deals with not interlining, make certain to allow time to retrieve and check your bag at the intermediate point as you are not a connecting passenger.
I went prepared to pay for extra weight / bags or reshuffle to hand luggage, however it was not an issue and extra bag and weight was checked through HND - LHR - DUB, with the last leg being in economy on separate PNR. So, it seems in this instance the check in agent took the path of least resistance and did not enforce the baggage allowance on the separate ticket.