Buy a copy of RF-8 it's designed to work with Windows 10 and has the necessary DX9 files it needs integrated with it's install process so you don't have to worry about doing something wrong, and RF-8 is a very nice upgrade for you. It's okay to have DX9 installed with DX12 if it's done properly so don't worry about that part.
i was thinking of looking at rf8, let me ask this, does it integrate or replace dx12? meaning after its installed and running, when i look up on my computer will it say i have dx12 or will it say dx9? not sure how much difference there actually is, reading stuff online some say 9 is good, just some visual lighting effects were better in the newer version, not sure its something i would even notice since rf8 is about the only "game" i see using anyway, im not into all that other gamming stuff out there but i am curious if it will replace 12