The document that settles it is a Real Property Report or surveyor's certificate prepared by a Saskatchewan land surveyor, showing the buildings, fences and improvements against the actual boundaries from Information Services Corporation title. Buyers' lawyers commonly ask for a current one, and where an old report predates a deck, a garage or a fence replacement, it is not current for the purpose.
Encroachments have standard fixes and they take time. Depending on what is over the line, the remedy is moving the structure, registering an easement or encroachment agreement with the neighbour, or in some cases title insurance accepted by the lender. Each of those requires cooperation or money, on top of the $800 to $1,500 a straightforward Saskatchewan legal file already costs, and a neighbour with no reason to hurry becomes the reason a possession date slips.
A shared driveway needs the same treatment, with use and maintenance written into a registered agreement rather than left to goodwill between the current owners. Sort this out before listing, not during the condition period when your negotiating position is weakest. Joel Dyck raises the survey question with sellers early so it never becomes the thing that reopens the price.