No TSK line and VPI line are NOT compatible .
But TSK is compatible with Jolliff line if im correct .
(someone please correct if im mistaken ) .

if you want to produce axanthics your best to breed 2 TSK lines
or
2 VPI lines together
just make sure if dealing with Hets they are actually het for it .

and as far as paperwork that pretty much intended for Hets . if you purchase the actual morph paperwork isnt needed cause the proof is already in the snake . but its always good to ask what line the are from when purchasing the animal.
9 x out of 10 when your buying the actual morph it will be listed or written on display what line they are from ..