Alli,
What I think has happened is when Eliza b:1848 was born in Wales they baptised all the older children at the same time as Eliza.
For that era, it makes you wonder why they would travel all the way from England to Wales for a few years and then travel all the way back again. It certainly would have been one heck of a journey to take with such small children.
I know looking at Australian travel back then it was a huge thing to travel between townships and states (counties) by either foot or bullock and dray. Even now I travel 4hrs to see my parents in the country by car, back then it would have taken many weeks if not months because of the mountains that needed to be crossed, not to mention a ocean inlet.
Regards
Anja
sounds to me like they were in wales by 1848 cant find the older children that say they were born in cold ashton. 
regards
alli