Change of format

I am thinking of changing the format of my novel. I want to put in 5 flashback chapters. They would show they most important parts of Allie's and Spencers backstory. I haven't written them yet so I will have to see if it works out.
I did write the whole prologue today. It is 1500 words. It has a short section at the end from the villan's POV. At the end of the novel there will be another short section with his POV before he dies.