OK, maybe it is not very clear how it works, so I'll try to explain:
you have 25 points in 8-ball GP
http://www.flyordie.com/grandprix/2016/8ball.html
and 16 points in pool (excluding 8-ball)
http://www.flyordie.com/grandprix/2016/pool.html
therefore the 16 points in your "pool" GP is not added to your overall points, only the 25 points for your 8-ball GP.
This can change, however, if you win another (non-8ball) pool event, and your pool GP points will be higher than your 8-ball GP points.
Hope it is clearer now.