I'm sorry I didn't read the whole thread and I know this is late.
Why not provide two versions of Delicious Library Inf? One costs $20. It only works/installs correctly if you have the original app. The other one costs $40. It is a standalone app. Make a minor bugfix update that says "hey" to the users of Delicious Library 2, and link to the expansion. Sell both.
Why not provide two versions of Delicious Library Inf? One costs $20. It only works/installs correctly if you have the original app. The other one costs $40. It is a standalone app. Make a minor bugfix update that says "hey" to the users of Delicious Library 2, and link to the expansion. Sell both.