"I feel like i feel my chest better and i can gain more muscle mass in shoulders with dumbellsdumbbells"
Probably the wrong forum to ask something like this.
Besides, if you can't "feel" your chest after a PR set, FSL, Boring But Big, etc. it is hard to fathom what dumbbells will do for you.
On to the bigger question: why not try it and see like Bartman suggests? Try using them as assistance with 5's pro and calculate the % based on your single arm presses. The program police won't find out - I promise.
By the way, you will NOT gain more muscle mass substituting for compound movements - no way.