Yes, I've been looking into that marriage, the ages work out ok (Elizabeth was baptised in 1812) and the witnesses were John Davies and John Owen. Elizabeth had a brother John and also her mother (Sarah was an Owen)....again, not much to go on unfortunately!.
I noticed on Ancestry that quite a few people have the (b c 1797 - Thomas & Elizabeth as having the marriage of 1835 in Llangranog. They had quite a few kids before their marriage, would this have been the done thing in those days?
I also couldn't find the (born c 1812) Thomas' in 1861 Census - but I did find in the 1891 Census that Jane Watkins was living with the elderly Thomas EVANS & Elizabeth Evans aged 80 & 81 and also born in Llandysiliogogo and Llangranog - unless this was a mistake I think they were Thomas & Elizabeth Thomas and not Evans.
I also found an obit for Elizabeth's sister Mary Griffiths (the Miller's wife) who died in 1895 and luckily there is a mention of Elizabeth and another sister Magdalen (died in August of 1894)which states that both sisters' passed away within a few months of Mary (she died in March 1895) ....so that narrows it down to 1894 or so. Not sure whether to look for Thomas & Evans??? Probably look at both just in case!.
Thanks for your help!. This saga continues!!!.

Webby