Hmm... did you try the option in Safari preferences -> General where you can set Safari to open links from (other) applications in a new tab in the current window, rather then in a new window? Edit: That didn't seem to help in a little test I did...
Maybe it's better to add all those links to a Bookmarks folder placed in your Bookmarks Bar, then set the Auto-Click option on that folder to open all the links in the folder in individual tabs... that I know will work... 😉