Acts 15:16 quoting the Septuagint Amos 9:11-12

[Richard Biss]

Somehow this question posted before I was done with it. Lamsa's Old Testament for Amos 9:12 has "They shall possess the remnant of Edom, similar to the Masoretic text. I was told the Septuagint has "the rest of mankind will seek the LORD," similar to what is in Acts 15:17. I was wondering if anyone knows if this Septuagint text may have been altered to go along with Acts, or if maybe another Aramaic text has a similar rendering, or maybe another Hebrew text or fragment found in the dead sea scrolls. This seems to be one of the favorite proof texts of Greek primacists.
Any help with a reason that James' quote in Acts 15:16-17 seems to fit better with the LXX than the Masoretic text would be much appreciated. Maybe the Masoretes changed Amos 9:12 because they would rather have had Israel possess the remnant of Edom, than have Gentiles seeking HIM?

Thanks for any help you can give,

Richard Biss