Hi there,
Welcome to Rootschat. I'm sorry I can't help you very much about this particular family.
However, you are correct in that they opened a brewery. I have a bottle at home with "John Fox, Castle Hill by Ewloe" thereon.
I am assuming this contained beer as I know there was a brewery at the location.
Ewloe is not too distant from Sealand. The name Fox is quite a common name locally.
If you have a look at
www.archivesnetworkwales.info and search for Castle Hill Brewery it will give you some information as to what is in the Flintshire Archives in respect of the brewery and the Fox family.
Good luck.
