South Derby recovered from 7-1 down to 7-5 at one stage, but in the end couldn't keep pace with the Scots, whose scorers included Felix Charlton (4) and Lewis Pritchett (3).
Invicta Marlins and Grantham were level at 8-8 with less than two minutes remaining. Then two goals by Dan Bonthuys clinched a vital 10-8 victory for Marlins.