My Stilwell and Harding families lived on the boundary of Sussex, Surrey and Hampshire.
Many of them were baptised and buried at Linchmere, which is in Sussex, but others are found in Frensham or Haslemere (Surrey) or over the border into Hampshire.
I have a very useful map showing the parishes adjacent to the county boundaries. I helped my to understand the geography better when I first started researching them.
We also have a similar situation now we have moved here - just 4 miles down the road Berkshire collides with Surrey and Hampshire. The attachment shows this well:
https://www.legislation.gov.uk/uksi/...ade?view=plain