JB wrote

stop at East Croydon). But the ticket office at the FCC station told
me I was better getting a Boundary 6 to Redhill.

I did ponder whether it was a valid combination for NCOC 19, but if
you are saying that it is not a combination, but should be considered
one ticket, that makes sense.

*location removed as I wouldn't want the FCC station to get into
trouble for suggesting cheaper tickets.

All National Rail ticket officers are supposed to suggest a cheaper
ticket if such exists and, eg, Which? will sic their mystery shoppers
on them and berate them if they fail.

Multiple tickets can be suggested too but are not required know-how.

--
Mike D