Problems Synchronising Sample Triggering

Hi guys,

I am a music student and working currently on a patch for university. The idea is to have 6 sample playback engines (groove~ objects) 2 for beats, 2 for bass and 2 for melodies. You should then be able to play them together in any combination. I managed to get the two groove~ objects going loaded with the beat loop samples. always just 1 is playing and if the other one is triggered the other one stops and so on. My problem is although to be able to trigger a sample but the playback of it starts only in time when the other one is finished and about to loop again. this should allow to change the beat samples in time seamless to not get out of time with the bass playing to it. i tried a few gate and counter combinations but it won't work properly. The loops are in the same lenght and tempo to make it easyer. Would be lovely to get some help or ideas how i could solve this problem.