Smart Kids!!
.... daughter for your screen name and son for seeing train tracks in the blanket stitch!
If you want to really impress your son, check your stitches and see if you have a double sided blanket stitch. Mine has that one, and it comes in quite handy at times. Run two of those side by side and you really would have train tracks ..... and those appliques would be nailed down for sure! It'd be a little tricky to get them to run in sync, but you could make it work in the odd spot, I am sure!
Good Luck!