Pretty designs!
It looks like you already sashing in between the 9 blocks. If you want it wider you have to cut the blocks apart, right?
I would turn those corners so they are on the bottom. Can you do the FMQ on the corners and then decide how to position them when you piece the blocks/borders.
How about this suggestion? Trim down the pieced border pieces (keep a seam allowance). Add a strip of purple fabric (width of blocks). The purple and the EMB side strip blocks would equal the corner stone so they can be pieced.
Square (Purple Border) Square
Corner (EMB Sashing/Border) Corner
Have Fun! Love your projects!
PS: I make individual quilt blocks when using EMB machine. Trim with a 1/2 inch seam allowance. If I mess up a block during the stitch out, there is only one block to re-stitch. I use no show mesh as the stabilizer. It stays right in the quilt. I trim it out of the seam allowance to decrease bulk.
Good luck!