With PrE, the DV-AVI (for SD Projects) Export, and then Import into the master Project, is the only way.
PrPro allows for an easier process, but that's one reason that it costs so much more.
Now, many editors have used a utility, Clipmate, to Ctrl+C/Ctrl+V Timelines into the master Project. I have not used this, so cannot comment. Still, there are several threads on this, and the Muvipix forum, on doing this. Robert Johnson was very active in many of these.
Good luck, and sorry for the bad news,