Aisle 2C: may be not so. If you buy a seat for a musical instrument you do not get the baggage allowance for that seat. IMHO that is bordering on ethical/moral breach of contract. The seat price includes all the goodies. What you choose to do with that seat is up to you, if legal. It would be an interesting test case if any one chose to test it. Mind you, same goes for no pooling of baggage within a group for whom one person paid all the tickets. That would also make an interesting test case.