The logical short answer is "yes"What if ONE person in a party is late, due to train delays, and the party can only travel together. I take it ALL can get the next available train when the latest person arrives ?
However it would be prudent to present the tickets and details of the problem to a member of staff and
seek advice.
This happened to a group of us before; to cut a long story short we were allowed to wait for the group member.
But without a full scenario being posted, we can't comprise a fully comprehensive answer.