Yes, but you need to get to them from Application Studio directly.
Open App Studio, turn on your filters, and filter by “startproduction”
Below is an image showing my filter results with both the base epicor layer and my custom layer.
Sorry… didn’t finish… and it posted… stay tuned while I type up the rest 
With that layer published and added to your menu… you now need to also edit your main MES screen.
So, you pull MES up in App Studio.
If you look at the stock event that MES uses when you click the Start Production Activity button… you’ll see the below.
The “App-Open” widget in there is opening StartProductionActivityEntry… but it doesn’t call out any Layers… so, you have your new custom layer made and published, but the stock button is calling the stock StartProduction.
You need to create a new event… that event will need a trigger to override the stock event… OR (what I did) was I actually created my own “Start Production” button, then on-click event of MY button… I have an event that includes an App-Open (just like the stock event), but my App-Open includes the name of my custom StartProductionActivity layer.
… then I just hid the stock button.