Yes, Robin - Rosie99 and I have all these details.
But if you read the other thread I quoted, you will see the correct birth ref for Ada.
Her mother, Mary, was Mary Smith.
She was born Ada PAY and used her mother's maiden name on the children's birth certificates.
Her father was George Pay, a coachman, and she quotes his name on her marriage to George Marling but changes it to Smith to match what she'd previously said.
If you read the other thread which I mentioned, you will see the thought processes.
And yes - William James apparently died before 1881 when Ada is a widow. But the 1874 death for a William James Pay is not the correct one, as that is for an infant of 0 years.