Love Dresdens and yours is spectacular!

It's gorgeous! I would applique the corners the way you originally planned to. There's no reason you can't.

No one will ever know there was to have been appliquéd Dresdens in the corners. Whatever design you chose to insert in the corners will look like it was planned that way. After seeing what you've already done with this quilt, I wouldn't begin to advise you - the designs you have already done tell me you'll pick the right ones for the rest of it!
Also...thank you for telling us you marked that whole grid first. That gave me a "whew" (so that's how it's done) moment! Love your quilting.

It’s really beautiful

How about a smaller star in the corners, similar to the stars in the center?

I thought the corner was another blade you were going to turn the opposite way. If that is so, and you appliqued the other pieces after you sandwiched, what's to stop you from adding those corner blades now? (Or, am I not remembering correctly?)

bkay

Your quilt is awesome. I do not have the courage to tackle a Dresden plate quilt.

I think it looks great the way it is without the dresden plates in the corners. As you have lots of white space around the center plates this makes the corners look natural.

you are remembering correctly, but I lost the blades, and only realized after I had put the binding on LOL