They don't fit. Although she did 'The Plank' with her little feet to make it difficult, bless her.
You can see how they go together. Sew the tops together... top and lining around the ankle, having the strap pinned in place. Then sew the sole to both (top & lining). I'd be stitching the inner sole (lining) over the seams inside by hand, if I was going to bother finishing them that is. You know, tuck the seam inside the sole lining.
I made the strap longer than before but stupidly didn't measure and left the full extra bit in... easily remedied but not now.
Back to the drawing board. At least they'll be easier, being bigger.