This is the unlikely breakthrough when, for a miracle, Yardley Hastings burial registers actually provided relationships:
https://www.ancestry.co.uk/imageview...043?pId=755956
Ruth, wife of John Underwood, was buried 12 September 1828, aged 23. The burial of her infant son was recorded on the previous page.
Here is the marriage of Ruth Crackstone to John Underwood of Yardley Hastings
https://www.ancestry.co.uk/imageview...38?pId=3703115
It takes place at nearby Bozeat 12 December 1825. John would have been 18.
And here *loud fanfare* is the baptism of Mary Ann Underwood, daughter of John and Ruth Underwood on 25 December 1825:
https://www.ancestry.co.uk/imageview...25?pId=2707616
I speculate that the birth took place under the roof of Ruth's parents, William and Mary Crackstone, in Bozeat.