A few ways to do this. But perhaps the easiest:
SAMPLE EDIT > CHOP (hit TRIM twice). Create your slices there, turn off LINK SLICES if you wish to create overlapping slices. Manually create extra slices using SLICE+ or pencil tool etc. Once happy, SHIFT > CONVERT and select 'new drum program using slices'.
At this point you can either choose 'non destructive' or 'pad parameters'. If you choose pad parameters you can continue to tweak the start and end points of each chop directly within the newly created program itself via PROGRAM EDIT > SAMPLES.
If you choose 'non destructive slice' you can edit each slice independently via SAMPLE EDIT > PROGRAM
Both methods mean each pad acts completely independently, any edits you make to one pad will not affect any other .
Check out my MPC Bible for more chopping tutorials.https://www.mpc-samples.com/product.php ... ive-bible/