Wood flooring issue

[Rich9995]

Hi folks, I've got a question about a flooring issue I have in my living room.. the house had an addition put on years ago, so they added flooring now there's a seam seperating the 2 types of flooring that are present due to the addition. It continues down the whole length of the room and there's a high traffic area that has a bad couple of floor boards. I'm not really in a position to totally rip out the floor and replace it all..the other side of the floor is still fine and solid, it's that 10' square part that is just not the same quality.. Is there anything to eliminate the creaking? Possibly an epoxy leveling compound that can seal things up, level the floor as to allow new flooring to be put down? The creaky floor boards are primary concern I suppose.. any suggestions are appreciated, thanks.