I set LDB as an emeded relationship in the web interface laster week. While it didn't imidiately show up on the page, it did after a few days. There where no changes to my .pkgmeta. The reltionship is there on the project page as well as the reverse from LDB project page.
So me thinks alot of this pkgmeta fkery is un-needed.
The project page listed relationship of the latest "default" package (the one that is available from curse.com), so either latest release or latest beta if no release package exists. In short, you should :
1) edit the project default relationships so future packages will get it.
2) edit the latest release/beta relationships so the project immediately get it.