i havnt managed to narrow down an 1861 census for either Robert hughes or ann owens.
they did not marry until 1862 according to the 1911 census records (1911 census says how many years they were married). and i didnt get any hits for an online search for a marriage on the BMd apart from the one in betws, but all the census' write that ann owen-hughes was born Llandudno.
so then im guessing the betws marriage is not them. nor have i found any hits for robert hughes in anglesey Llangefni as i dont have his parents names and none come up to that place name.
so furthest back i have with any confirmation is the 1881 census for them in Llandudno. living at pen y beurth
ive just found a baptism record for their daughter margaret ellen b 1873 in liverpool, and i am guessing as robert was a journeyman stonemason. he probably went where there was work. as he was previously in manchester, when ishmael was born 1867 , all the other children were born in Llandudno and were later than the two i have just mentioned. (richard 1863 was earlier before he went to the north west and a year after their marriage).
i feel, that anne was born Llandudno, and would have thought she would marry there. but as i say i havnt got anything further back than the fact that son richard was born to robert and anne in 1863 in Llandudnop via the census recs.
or the name of anns mother

so it could be the mary you mentioned i will try looking her up on the census and see if theres any ann/annie as a daughter.
i was trying to find a marriage record that might have had the parental names on it. sometimes it happens!! if the parish/church recs are available online.
i am just amazed at how much has come to light already.