[Michael Stavish]

I’ve refined this to a full steps process, including reordering the markers and regions at the end, if you want. I originally wrote this for Video Stack Exchange.
Here are the following steps to merge project A with project B into a new project C, copying all clips, markers, and regions:

1. Copy all the clips from project A timeline.
2. Turn on auto ripple on project B. Make sure to select “All Tracks, Markers, and Regions” in the drop down.
3. Paste the clips from project A (copied in step 1) at the beginning of project B. All project B clips, markers, and regions should have been shifted to the right. All project A clips are at the beginning of the timeline on project B, but the markers and regions have not been copied.
4. Save project B as a new file, project C.
5. In project A go to View > Window > Edit Details or type ALT+6.
6. In the Edit Details, select Markers or Regions, whichever you want to copy, in the “Show” drop down.
7. Select all the items by clicking the empty space on the header row in the first column.
8. Type CTRL+C to copy the items.
9. In project C go to View > Window > Edit Details or type ALT+6.
10. Select Markers or Regions, whichever you copied from project A in steps 6-8.
11. Select the first empty row, then type CTRL+V.
12. Repeat steps 6-11 as needed, to copy all markers and regions, whichever you haven’t done yet.
13. project C now contains all clips, markers, and regions from project A and project B. Don’t forget to save your work.
14. Optionally, you can re-order all the markers and regions in project C. Simply select all the rows by clicking the empty space on the header row in the first column, then type CTRL+X then CTRL+V.