Electrical Main Panel

Hey Fellas,
Thank you for all the advice. A LOT of help here! I am going with the suggestions of using the space freed up by the breakers in the main panel moving to the sub to put in my 100 AMP breaker to feed sub. I think that its the safest way at this point although I am very interested in your MO there Heel bear toe @Treblig. This is the way I am going at this point to get things up and running. The feed line has to be run either way. I can always pull a permit later to change panel and make the feed line to sub "go away" if I dont want to draw attention to the remodel. I think the intention of the permitting process has its merits and intention is to keep things safe, although I have a few opinions (based in possibly not enough information) about other things like who wrote the code on AFCI? Where they greased by the breaker industry? And....What happens if the permitted/inspected FLOW GUARD CPVC pipes fail? I mean, they passed inspection so........well it wont be the city. So yes leave line voltage to the pros....for now. Or be ready and waiting with all the stuff ready to go and then when the power goes out I can pull the meter, swap the panel, and leave the seal on, but clipped. They dont come around much and when they do......must have been those darn kids next door.:rofl:

But sincerely,
Thank you, I knew I had asked the right people.