MArriage between step children?

[Trees]

Would it have been possible for a man to marry his father's step daughter in 1823?

[medpat]

Step siblings are not related so I can't see why not.

[groom]

He couldn't marry his step daughter, but no mention of stepsister, which is what she'd be.

http://www.genetic-genealogy.co.uk/Toc115570145.html

[Ruskie]

Isn't a man's father's step daughter, the man's step sister?
snap groom ... (and I was just about to post the same link)

I am surprised that a man is allowed to marry his step sister. 

[RJ_Paton]

Would it have been possible for a man to marry his father's step daughter in 1823?

Yes, legally the laws of Incest didn't apply unless the siblings shared a common parent, the biggest hurdle for them would have been the reaction of family, friends and society in general if they knew

[Trees]

Thank you that was the way I was thinking but some of the old restrictions seemed odd so thought I'd better check they had no common blood.

[groom]

If you think about it, if you can marry a first cousin, where you share grandparents, why can't you marry a step sibling where you don't share any ancestor? I suppose the only restriction would be if your parent had legally adopted that step child as they would then become your sibling. 

[Trees]

Its an odd situation Henry FLAVELL married Mary Guest Henry died in 1811
William Flavell (a cousin of Henry) married Lucy Guest (sister of Mary) Lucy also died in 1811
William and Mary had a child in 1814 but married in 1837! with son Dennis acting as a witness.
Meanwhile said son was widowed and married one of Henry and Mary's daughters in 1823
but as the son was not baptised I am trying to prove he was William and Lucys child.
Its well before formal adoption isn't it?

[groom]

Yes, formal adoption started 1927.