Hi Heddwch,
Hopefully with the aid of a certificate you will be able to fathom out the relationship of these people to your Connick family...could be that the boys mother was a Jones before she married.

1901 Neath Road.
RG13/5055 F36 P16
David Jones/H/S/30/ Ch? weigher colliery/Aberdare, Glam
Elizabeth Jones/sister/S/35/Dressmaker Onllwyn Glam
Jennet/sister/S/22/ gen servant Blangwrach?, Glam
Hannah/sister/S/17 Resolven, Glam
Isaac Connick/nephew/8/ Onllwyn, Glam
William Connick/nephew/6 " "
I don't find it odd that they both married girls named Gwenllian, with the family naming pattern in those days so many people had the same first name...
I am not sure if it would be possible to get a list of people, perhaps you could ask that question on the Glam board.
Ambers