We're about to start DIY replacing our kitchen & adding a wall/laundry room. My top choice for flooring at this point would be Coretec in a stone print since this floor will butt up against an existing hardwood foyer and other carpeted rooms. House was built in 2002. Current floor in designated areas is sheet vinyl over what I think would be 5/8" tongue in groove ply with 1/4" luan. (see photo from below) Subfloor is glued & nailed/screwed to joists, glued at seams, luan looks to be glued (from visible glue overflow at the floor registers). There is a load-bearing wall (blue in drawing) that runs halfway between the kitchen & sunroom, subfloor runs under this wall. New partition wall to be built (green) to run parallel to joists in the sunroom. The sunroom joists are all sistered (due to an 18" extension that was done by original builder before house was 1st sold), between 14.5" & 15.5"oc measuring the closest joists together. In the kitchen the joists are single and range between 14.5" oc & 17.5" oc. Some of the joists in both the sunroom & kitchen have plumbing/hvac running through. There is only 2x10 blocking near the 2 i-beams supporting the back of the house & the front of the sunroom, and some (but not all) 2x4 blocking at the end of the original joist before the foundation. Every gap between the joists in both rooms has sagged with a difference of 1/16" to 1/4" depending on the spot, even the 14.5"oc has 1/4" sag. There is deflection felt & squeaking heard when walking through the kitchen due to the 17.5" oc. Removing the current subfloor does not seem viable, when we removed water damaged subfloor in an upstairs bathroom the glue was stronger than the joists, they split and we had to sister 2 new joists & add blocking under the bathroom. Due to the open layout, unsure that adding another 5/8" ply layer is a good option either due to the carpet/hardwood in the other rooms. Obviously we need to add blocking where we can to prevent further deflection. What are my options to get this floor flat to allow the floating floor? Thank you for your help.