Not sure if this is what you're looking for, but here's hoping.
Draw up your 8" square, marking at 2,4 &6" on all sides.
Divide into 4 equal squares.
Now mark each line at 2" from the center and connect the dots. This is your center square.
You will have to measure the sides of the square, and cut 1/4" larger all sides for seam allowances.
Do the same with the 4 tie and background squares. This should give you the correct size pieces for set-in seams.
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