Hi grumpyblondie,
There is a James Brownhill son of James Brownhill of Stockport baptised 19th February 1718 (old date format) at Stockport - or one in 1712 son of Peter?
A James Brownhill married Martha Smith at Bowdon 1st May1707.
There are some Brownhill wills that might help, but I can't see anything obvious. The index is available on the Cheshire Records Office site but FindMyPast now have the index and the images of the wills so it might be worth a small investment.
There is a 1604 will for Christopher Brownhill of Northenden - it might be worth a look in case you can move forward from it if you are stuck going backwards.
Jean