Upvote:1
You can not short check one bag to a mid-flight stop and check the rest to your destination. Checked bags always go to the end destination of the flights you are taking.
You can check an additional bag at B, but it will be subject to the original check in rules. So if you checked the full number/weight allowed at A, then you will pay the excess baggage fee at B, if you don't check your full allotment at A then the bag at B may be free.
Plus you need to get that bag of goodies to B π