We had a 12 pt. system league in one of our houses and it went like this.  First game, worth 2 points-was a team game.  Second game, was doubles--first 2 were a team and second 2 were a team--each doubles score was 2 points.  Last game was all singles--worth one point a piece.  <you bowled the person across from you>  Overall total was worth 2 points.  Higher average team put line up in first, just in case the lower average team wanted to adjust their lineup.  All scores were with hdcp.  It was a fun league that everyone enjoyed.  Hdcp percentage could be anything you want.  It was a late league that is why we don't have it anymore.