Would this be a valid formation?

-------ST-------
AML--------AMR
-------MC-------
--DMC---DMC---
DL--DC--DC--DR
-------GK-------

I have DMC/DC youngster and I want him to get playing time so he can develop quicker. My 2 DC starters are too good to bench for the youngster. The AMR I have is a youngster who can also play AMC, but I want to have wingers. Idk if I should change my Wingers to ML and MR. Then change MC to AMC so the youngster can play.

Yep...

it also depends on form, one of your players might have a bad season in form, so then you can bench them