We share our drive way with our next door neighbors and it’s frequently blocked by their vehicles and those of their guest.

What legal rights do we have to prevent the neighbors for parking is the shared or the common space driveway, which creates problems? We have a two signs posted in the driveway “No Parking in the Shared Driveway” but still it happens often.

You need to describe the driveway more. How wide is it? Does it lead to garages? Is there room for 2 cars to park side by side? Might help if you attach a picture.

But the bottom line is if this is shared and they are blocking it so you can't access it, then you may be able to have the blocking vehicle towed. I would go to your local police department and ask them what the laws are on blocking a private driveway. You may be able to call a tow and have the vehicle towed. You would need to put up a sign to that effect first.