Why won’t Southern Rail let me make a joint claim for a delay?

We bought two tickets on our Two Together railcard but we have to claim separatelyMy husband and I travelled from Bexhill-on-Sea to Brighton using our Two Together railcard. My husband purchased our tickets. Our return was delayed due to a points problem and my husband made a Delay Repay claim. We have done this several times before and never encountered a problem. Southern Rail has now decided that both travellers must make a claim to receive compensation so they have only paid for my husband.