You could hard-link the schematic between the different projects (use 'junction.exe' on Windows).
being new to PSoC Creator
Can you explain a little more what exactly needs to be hard linked to make it work?
All the Best
Create two projects. Then remove the schematic file from one of them, and use junction.exe to create a hardlink to the other projects schematic instead (using the name of the deleted schematic).
Note that not all programs will be able to handle this properly, e.g. you should exclude that file from source control.