DL-DC-DC-DR
----DMC----
ML(or AML)--------MR(or AMR)
----AMC----
--ST--ST--
I 've always wanted to run a 41212 formation, but don't know if I would be penalized. Instead of having my winger in a normal Left/Right Mid, can I push them forward in the attack position?

I also have some pretty good MCs and I don't want them to go to waste, so can I run these formations?
DL-DC-DC-DR
----DMC----
ML(or AML)--MC--MR(or AMR)
--ST--ST--
or
DL-DC-DC-DR
ML(or AML)--MC--MR(or AMR)
----AMC----
--ST--ST--

In order to have a valid formation, what are the rules of the midfield?