Hello Mull,
I apologise for not getting back on the Board regarding Phoebe Roberts. I did look for her a few times but then came down with a lurgy that lasted for two months, so there was no progress afterwards.
It proved impossible to locate a marriage for Phoebe Roberts with any degree of certainty. I couldn't find anyone of that name marrying on Anglesey. She is in Llandegfan with her family in the 1891 census and she is there in the 1901. In 1901 she is aged 42 and Theophilus Roberts, age 16, and an Apprentice Blacksmith is in the household. I found her eventually in the 1911 census, she is transcribed as Phoche Roberts and I found her only after searching for Theophilus, her son. They are living in Bodwilog, Llandegfan, Phoebe is shown as single, age 53, the occupation given as "Farmers" and for Theophilus "Farm son working at home". So we know that she hadn't married up to 1911 at least.
The 1921 census might help us when it is released but it looks as though she didn't marry and lived with her son until 1911. I found two marriages for Theophilus Roberts in Bangor Registration District in 1916 and 1917. It is very likely at least one of these is her son.
We had a rough time of it having had two storms in less than a week. I am in the Southern Uplands and being high tends to catch the worst of the weather, high winds especially.
Helig.