I think if you each bought tickets from your respective stations (Garforth/Castleford) to Leeds and then a 2Together from there, and bought them in one transaction, that is good evidence of one contract for each customer to be conveyed from their respective origins through to London. A
lthough it's arguably a matter between customer and the relevant TOC(s), a good retailer might be prepared and able to back the customer up in the event of a dispute (I am aware of instances where this has happened), so choose the retailer with this in mind. It could be bought online, or perhaps at a station whose ticket office staff agree that it is a valid set of journeys and who are prepared to issue paper itineraries to accompany the combination of tickets.
However if one or more of the ticket holders has a Season ticket/product such as a Metro Card, then it is
harder to demonstrate this contractual entitlement. However I do not believe the principle to be any different, and you should still both be conveyed, in my opinion. However the chances of an argument are greater.
I strongly disagree with
@Bletchleyite's position in this thread.
As for 'excessing away' a discount at a ticket office, I do not believe the customers should be required to do this against their will due to a delay to one of the passengers, but if they
choose to do it, a
decent TOC will do it, e.g. LNER will do it (do LNER still have a travel centre at Leeds?). Unfortunately many TOCs have a poor policy in this area and won't do it, which says a lot about how bad those TOCs are, so the chances of success depends on how reasonable/sensible the TOC operating the ticket office chooses to be!