I'm still hoping there is a tool that can do this process, but I found a simpler way to do create a feature footprint using buffers. I created a buffer with a large enough distance to cover the smaller empty spaces, like 500 meters (attach 1). I created another buffer of the 1st buffer using a negative number for the buffer distance, like -500 meters (attach 2), to get back to the extent of the parcels (attach 3). The result isn't a perfect footprint but it works for my purposes and it's quicker than digitizing, merging, etc.
Charlotte