IDE and projects sharing files

I want to create a new project that references severa .c and .h files in another project. They are both in the same workspace. I only want to import into the new project files that I will modify. The others just leave in the other project but include them in my new project. Is there a way to do this?

I am using NIOSII IDE:

Version: 5.1

Build: 112.4

thanx