Who's driveway?

Long story short my sister own a house with two driveways. She has lived there for 10yrs.

Both homes next to her have their own single driveway. My sister's second driveway goes to the back of her house to her detached garage.

New neighbors move in and immediately come over to tell her they own the part of driveway. The part closest to the street and My sister technically owns the back half.

The neighbors had land surveyor come out and spray paint properly lines. So now this neighbor parks in that driveway even tho they have their own 😢

Like they park so their tail end is almost in the street and the rest of the driveway to the detached garage is blocked and since they own that part its like they doing just to assert dominance.

My sister doesn't let it get to her but it pisses me off to the core.