While we are not equipped to advise anyone on this we can reccommend a few great resources.
The first is Nolo Press' helpful legal primer The Sharing Solution covers yard sharing among other sharing projects.
Other Legal Resources:
Though these books are not legal in focus they do give a in depth look at how sharing and a new perspective on "the commons" are changing the way we think about thriving in the rapidly changing world. If you would like a real boost in your thinking in terms of abundance rather than want, these are wonderful starting points.