I have a Margaret Brownhill, but born a generation earlier, in 1788 in Meigle. She married in Dundee, where the family had moved, Her father was Charles Brownhill. I suspect his wife was Agnes Henderson. Charles and Agnes had several children, including at least 3 sons who would have carried on the name, They were:
WILLIAM BROWNHILL, born 1778 in Meigle. A certain William Brownhill died in Dundee in 1843. No parents are mentioned, but he is described as a "weaver and old soldier". At his time of death, he lived at Rosebank. Margaret's son also lived at Rosebank.
DAVID BROWNHILL, born 1780 in Meigle.
ALEXANDER BROWNHILL, born 1786 in Meigle
Brownhill is not that common a name. Perhaps one of the above is the father of your Margaret? Let me know if it proves to be the case.
Diane