Easement Issue In Oregon

Location: Douglas County, Oregon. Winston address but outside of city limits.

We share a driveway with two other neighbors. The driveway runs fully through our property. There was no formal easement agreement by the original three owners (two brothers and their friend). There is no easement agreement on the deed. One neighbor moved in around 20-25 years ago. He tells other people the driveway is “his” but has never discussed it with us. He actually claims around ten feet of our property past the driveway to others but again has never talked to us about it. He’s hostile. The properties have not been surveyed in around 50 years (we’ve been here 37 years) but every publicly available property plat and survey map shows the driveway and some feet beyond it to be within our property, including the original property map given to us by the original owner. Around 15 years ago, the hostile neighbor installed a temporary earthen speed bump without permission. My father didn’t want problems and elected not to assert property rights and didn’t discuss it with either neighbor. In the years since the speed bump was worn down, the same hostile neighbor has dug two or three ditches across the driveway as speed deterrents without permission. For context, this hostile neighbor is not civil. He’s verbally assaulted our other neighbor on the drive at least twice (once for driving a tractor on the driveway ‘too close’ to his property and once for weed eating along our side of the driveway with the hostile neighbor claiming it was trespassing) and the prior neighbor on the drive at least once (same story about driving a tractor ‘too close’) and once physically assaulted my mildly autistic brother but I’m not sure why. He also openly killed one of our roosters a long time ago. Someone recently shot out the back window of my uncle’s car and we suspect it was this neighbor. There is zero possibility of amicable discussion with the hostile neighbor. My father passed over a year ago, my mother now wants to assert her property rights. She doesn’t want them to alter the driveway without permission. What is our recourse?