Yes thanks for those suggestions.

Given the above, I'll definitely take his luggage using my allowance as I won't need to check anything in myself anyway.

Absolutely beggars belief that you can't interline bags on the same airline. Just bonkers.

Just as bad as when I logged in to some Club Europe tickets I bought recently for a couple of people who were not Exec Club members (in order to seat them together)
and BA wanted twenty quid extra per person (or whatever) to choose a seat

I guess I am out of touch.