How to export (PDF) a document with only part of the content

We are creating a document which contains two types of information/text, e.g. “theory” and “exercises”.
Once the document will be complete, we would like to be able to easily export in a pdf only one part of the information (e.g. the “theory”).

We have tried various avenues.
The one the closest to what we are looking for is to have the “theory text” in one layer, and place the “exercises text” at the right place in text objects in another layer. So, if we then remove the “exercise layer”, or hide it, we are left with the theory content and can export a pdf. However, when we edit the “theory text”, the “exercises text objects” do not move with the “theory text”. Given that we have a long document, it would not be practical to keep re-locating the “exercices text objects” each time we edit the “theory text”.

We have also tried to put the “exercises text objects” directly in the “theory layer”. This way they obviously follow the theory text when edited, but we have not found a way to remove all the “exercises text objects” in one go in order to easily export only the “theory text.”

Any suggestion welcome! Thanks!