When I looked at St Cath index (Free BMD)
FreeBMD is organised by Registration District - and as you say, Pentyrch was included in the Cardiff Regn District until c1934.
So are you saying you cant see them - use the '
@nnnn-nnn' option for a Death search - where the 'nnnn-nnnn' spans a few years around their known Birth Year - this will filter down a possibly large list (given the names involved) ...
If however, you know that they will be recorded in St Cath's Parish registers, that will help link to a GRO index entry, which of course you need to order a Death Cert
