Hi!
Depending on which layout options you mean, there might be possibilties to prevent that from happening, but in general you are right, that Dorico is not very forgiving, when doing major changes like adding pages after having done the detail-work.
We discussed this issue in this topic, especially the idea, of adding a way to “lock” the design, but this does not seem to be the plan.
This was basically the best answer I got: Don’t do things like additional layout pages in Dorico itself.
best regards