Thank you all very much for your responses and sound advice. Unfortunately in this case there isn't any evidence to support a late or group baptism as jane Stephens 1746 had brothers baptised in 1745 and 1750 at St Briavels, plus possibly two more brothers at llandogo in 1754 and 1756.
I'm not discounting that all of them may have been baptised late ... just have to keep searching

thanks again......Danny