How to automatically make new polygons in the space between other polygons

[ZacharyNeumannQK]

I have a parcel layer. My client needs me to make new parcels on the right of ways. The parcel layer has no polygons on the right of ways. 

I need to make polygons on the right of ways, and split those polygons into many little polygon squares. 

kind of like the image below, but they need to fill the space.

[JonathanMcD]

The Fill Gaps tool would be an option, but that needs a certain licence that's not even covered by Pro Advanced and Interoperability. What you could do, and it's a bit janky, is create a large coverage polygon and clip the parcels.

[ZacharyNeumannQK]

Clip the parcels how. I made a large coverage polygon, erased out the parcels, and have one big polygon for the ROWs, but the problem is it needs to be separated into blocks in a neat way. Is that impossible? Did my client do this by hand? I am at a loss for what to do and the client doesn't seem to know how they were made.