splitting a subdivision

I don't know Pennsylvania law, but if certain greenspaces or common area were apportioned and required in the original development plat, that might make it more difficult for a section to just split off.

We have a section (our subdivision was built in 10 phases, with each phase having it's own set of CC&Rs, but all under one HOA) that was bought from the original developer as raw land and then developed as what they termed an "innovative" subdivision, meaning they divided into much smaller lots (more dense per acre), and have smaller footprint homes and garages. One can almost stand on the property line between homes and extend one's arms and touch both homes.

After building the model home and about 2 or 3 others, that builder went bankrupt in our state and left the lots stand undeveloped until various individual builders snapped up pockets of lots and built a mish-mash of homes.

Our remaining 9 sections petitioned us to eliminate that section from our HOA but what we discovered was that, because a large portion of it backs up to quite a bit of our common area, including two lots that abutt our retention basin, we cannot "cut them loose."

I wasn't involved in the research and the project to try to so I don't know the specifics or legalities, but it boiled down to our subdivision requiring a certain amount of greenspace/common area for our footprint and we somehow run afoul of that formula if we cut them out.