You can only assign one course to a group. However, you can combine modules from different programs and create a customized course for your group.
Step 1. Click on the My Courses tab.
Step 2. Then click on the title of course you want to update.
Step 3. On the left side, you'll find all the modules you have created. This means all the modules for any of the courses on your account.
Simply click on the title of the modules you want you to include, then slide them over to the right by clicking the right arrow. Then click the Save button.
Relevant Articles:
How do I add modules to a Course?
How can I remove a module from a group?