Stop in for a cup of coffee

FML.
Wirking on selling my 40 acres of farmland to the guy that owns the land around it.
According to the surveyors, my sheds are on neighbour’s property.
Neighbour is freaking out.
My one shed has been there for 40 years and the slab for the grain bins same amount of time. We thought the painted post was the line, nope.
FFS, now i have to move 2 buildings and cut that 12” thick slab and apply for a variance due to a screw up someone made 25 or so years ago.