Hi there,

As you noted, each Punch program includes different features, as you can see and compare using this chart.

The Interiors program doesn't include Landscape and topography features, however, it includes a Plant library. If you buy any additional Punch program, it won't be integrated with the Interiors program (as add on) => it will be another program. But, you can create the project with Interiors => open the file with the new program => add the Landscape using the new program. In other words, you can move the files between programs (if they are the same version number)

Important note: The Punch programs' version compatibility works following the ascendant version number. This means that the old files are compatible with the new versions but this doesn't work backwards.
Therefore, a file elaborated with V19 (for example) can be opened using V20, but if you save the file using V20 it will not open with V19 (Windows or Mac).

Hope this helps.