Sorry, I should not have quoted from the 1939 register.
The birth registrations for Thomas Owen and two of his children are in the Anglesey birth index, showing that they were born on Anglesey. The details are:
Thomas son of William Owen & Kate Owen, 13-Jan 1905, Holyhead
Elizabeth dau. of Thomas Owen & Annie Roberts, 10-Feb 1930, Rhoscolyn
Ronald son of Thomas Owen & Annie Roberts, 2-Sep 1936, Llanfachraeth
It seems that Carol Owen and Annie Roberts were not born on Anglesey, I cannot find their birth registrations in the Anglesey birth index.
FreeBMD has a birth for Carol Owen, mmn Roberts, J,F,M qtr 1935, Heywood 8c 618.
On the marraige cert is has his name on it "Robert Roberts (deceased)". The family know he had passed by the time she was married in 1930. But that is literally all they know.
He is also down as having lived in Ty Weryl, Rhoscolyn as last address (according to the marriage cert.
The witnesses ain't as straight forward either. You have a 'William O Jones' and a name I cant make out. The surname is Roberts. Looks like Eirwen of something.
I think the marriage certificate will only show Ty Weryl, Rhoscolyn as Annie's address on marriage, not her father's last address?
I think I have found
a possibility for Annie in the 1911 census but I probably shouldn't post details.
If I'm correct her father's name is sometimes recorded as Robert Jeffery Roberts, he is a quarryman in Caernarvonshire and Annie has a younger sister Mair.
PM me if you cannot find the record.
FreeBMD has a birth for Annie Roberts, mmn Jones, O,N,D qtr 1907 Carnarvon 11b, 389 and a marriage for Robert Jeffrey Roberts and Maggie Jones, J,F,M 1907 Carnarvon 11b, 499.