How to change project location?

Hi Community!

So I had a single folder with a project file. Now I wanted to move that project contents into a new folder and add another folder that I have two separate projects under the same parent folder like this:

parent folder\
    - project_old\
    - project_new\
    - project_old&new.hzp

In the parent folder I left the old .hzp file and just renamed it and in crossstudio I added the new project to the solution.

After updating all the folder paths I rebuilt the old project and got several errors, because it still built the "obj" folder under the parent folder but not under "project_old".

How can I fix that relation?

Thank you.
Hannes