Without more information, it's impossible to say which of the multiple marriages of Jean Broomfield might be the right one.
There are also multiple Agnes STEELs, but I think I would favour the one chr. at Fogo, Berwickshire on 10th September 1786, daughter of Andrew STEIL and Agnes STEIL, who married 15th May 1779 at Eccles, Berwickshire. The marriage may have been one of necessity, as Agnes' eldest sibling Ninian STEEL was christened at Fogo on 21st December 1779.
Regards,
Lesley