I know you can set formation overrides, and make rules to select which formation to use for different situations, but is there a way to ensure a player gets on the field for specific plays using some combination thereof?

For example, I may want to use my SLB at the WLB position on 3rd down blitz plays instead of my WLB; however, I don't want my SLB in at the WLB position every time I call a nickel formation, and I don't to blitz on every third down.

In a nutshell, I want to blitz in certain situations and I want to blitz with a specific player if a blitz is called, but I'm not sure if it's possible to build this into a rule.

i don't think there is a way, i know irl you would have to be crazy to do that since as soon as a QB saw your SLB line up at WLB he would know a blitz was coming