On the 1851 Census HO107/1856/202 for Church Knowle I came across my GG Grandfather William Fry - Relationship to head of family was listed as son-in-law. There was no wife listed with his surname. The only daughter appears under her father's name. I know it could be an error in transcription.
On checking William's parents I found that his father had died when he was 2 and, from parish records, I'm almost certain that his widow remarried a year after his death and that William moved into the house with the new couple. (He was living with them on the 1841 Census too)
The head of the household was John Gook and it struck me that perhaps William was treated as his son, in law - (perhaps he was adopted by his stepfather or something less formal?)
Has anyone come across this particular use of the phrase "son-in-law" or am I barking up the wrong creek without a paddle? (:-)))
Any help would be appreciated