You don't state all the facts from the marriage certificate - it states Maria Farr, formerly Paul, dau. of Catherine Paul subsequently married to William Lawlor (checked and the latter took place in 1909).
The census showing Maria with John Farr and Catherine also shows she was born in Gourock, Renfrewshire.
Have found her birth entry:
Maria Gracie (?hard to read second name) Paul, born 11th March 1905 Greenock Poorhouse, Gourock, dau. of Catherine Paul, millworker - her mother registered the birth and signed as Kate Paul. I should also add that the birth has been indexed as Marie Gracie Paul but name is clearly Maria on the birth certificate.
I would suggest that Maria was informally 'adopted' by John Farr and his wife Catherine (I note on census it states she'd had 15 children with only 1 living??). If Maria believed John Farr was her natural father I'm sure she would have named him as such when she married. Clearly she was raised as 'Farr' by John and Catherine Farr but always knew who her real mother was. Adoptions weren't legally recorded until the 1920's so there won't a record of an informal adoption.
Can I ask when you ask for help as in this instance that you give us all the facts stated on certificates - i.e. married as Maria Farr, formerly Paul, mother Catherine Paul subsequently married to William Lawlor (does not state the latter was her father), and that Maria was born in Gourock, Renfrewshire. I had to look at these documents myself to find out this information.
So, Maria was born as Paul on 11/3/1905 and although her mother Catherine eventually married in 1909 Maria was raised by a John Farr and his wife and she was raised as a Farr but I do not believe that John Farr was her actual father, just an 'adopted' one. One find it difficult to see John and his wife had had 15 children with only 1 living and without checking back further to see if this was the case I'm wondering if Maria, shown as their daughter on the census, is being counted as the '1 living'!
Annette