No likely marriages for them in Maughold registers.

This looks like Mary Ann in the 1881 census:
Daniel CHRISTIAN Head M Male 32 German, Isle of Man, England Fisherman
Mary Ann CHRISTIAN Wife M Female 36 Maughold, Isle of Man, England
Philip Danl. CHRISTIAN Son Male 2 Peel, Isle of Man, England
Mary Eleanor CHRISTIAN Daur Female 1 Peel, Isle of Man, England
Jane Agnes QUAYLE Niece Female 12 Maughold, Isle of Man, England Scholar
Peter WALLY Boarder M Male 49 Ireland Stone Mason
Source Information:
Dwelling 33 Douglas St
Census Place German, Isle of Man, Isle of Man
Family History Library Film 1342344
Public Records Office Reference RG11
Piece / Folio 5597 / 45

Mary QUAYLE married Daniel CHRISTIAN 19 FEB 1876 Saint Barnabas, Douglas.

No bapt for the niece in Maughold, but she could have been born there and baptised elsewhere.
There were a lot of siblings who could have been Jane Agnes Quayle's mother or father.

James and John were living with their mother in 1881:
Mary (Catharin) QUAYLE Head W Female 64 Maughold, Isle of Man, England Housekeeper
James QUAYLE Son M Male 42 Maughold, Isle of Man, England Labourer and Brick and Tile Works
John QUAYLE Son U Male 20 Maughold, Isle of Man, England Farm Labourer
Source Information:
Dwelling Booleey Velt Cottage
Census Place Maughold, Isle of Man, Isle of Man
Family History Library Film 1342345
Public Records Office Reference RG11
Piece / Folio 5600 / 34
Page Number 12

Sue