firstSnapStitch 

If you want to do designs with features that Snap! has but Turtlestitch doesn't has such as multiple sprites or pixel related operations.You could run the first part in Snap! and the second part in TurtleStitch!You could also add the tracking blocks to a Snap! program in Snap! and output it with the tracks.Then import it into TurtleStitch to continue with stitching.