A sibling's birth:
Thomas Charles Stewart
Birth 4 Oct 1863 Port Glasgow, Renfrew
Father John Stewart
Mother Mary Crumley
From SP Index, the one you mention you found:
John William STEWART
Mother's maiden name CRUMLEY
1859
Ref 574 / 200
Port Glasgow
There is also an RC batism for this John:
John William STUART
JOHN STUART / MARY CRONLY
Birth 1/8/1859/ Bapt. 7/8/1859
Port Glasgow, St John's
Monica
PS: Have you managed to find them in the early censuses? I failed
