My final understanding of the easement agreement, I don't believe that they are
currently looking for a full block assemblage, though that could change in the future.
In red is the current footprint, 477 Madison in blue...
The option to merge the lot would give 350 Park a larger footprint from which to maximize FAR development (minus 477 Madison). The excess development rights could then be applied to the current footprint.
Beyond certain technical requirements for construction of a neighboring building, 350 Park looks to lock in views and light from the western (bordering) side of the building. The agreement also extends to any future development on the 477 Madison lot, including setbacks.
Very interesting, and excited to see where this leads next.