Plans For Sheds

Her father built the extention unto a piece of land owned by my father, there is no legal binding, but I presume that my father gave permission.[both are now dead] The land is currently farming land with out houses , sheds and the remains of the old house. I now wish to built myself, the daughter is objecting on behalf of her brothers[she doesn't live in the house] and is applying for squatters rights. The land is in my name, however I have no plans to distrupt the extension but have great objection to her claiming squatters rights on my current strip of land which is approx 30/40 metres square. This would greatly impact on my development and the rest of the site. I would gladly sign over the piece of land that the extension sits on as I believe this was a gentlemans agreement at the time between our 2 parents. The site is in current use [farming] including the narrow strip of land
.I would prefer to settle this without going down the legal route.
I would be grateful for comments.

I am currently renovating my property which is a 1 bedroom flat, We only have a small outside space that conist of a concrete area (approx 3×2.5m) and an adjacent area that has a shed on it. I have recently knocked down the shed as it was very old (made of rusty tin sheets etc), my idea was to but a wooden garden summerhouse that woudl fit perfectly on the spot where the old shed once stood. The problem being that the old shed was adjoined to a smaller shed that is owner by my neighbour, and because of the weird setup, If i purchase a summerhouse and put on on the old shed spot, the smaller building owner by neighbour would obscure the view and would restrict light coming into the new s/house. What do you think my options are in regard to asking my neighbour if he would mind me knockin down his small shed ? The neighbours shed is actually an old outside toilet and it measures only (1.5x1m) and is of stone construction. (roof&walls). He never uses it for storage and has only ever used the toilet when he was getting a new bathroom suite fitted in his house. Any ideas on how to approch him would be appreciated ?