either Swiss or Italian Meringue frosting? I need to fill some apple pie cupcakes and not sure if I should use pie filling or mix some pie filling in the frosting. Thank you.

I would fill with pie filling then frost with buttercream with added apple pie spice. Yum yum. I don't think I would add the filling to the frosting because that frosting in particular has a delicate balance and I think it would affect the texture or consistancey

You don't mix it into the frosting. Add it to the cake mix batter after all the other ingredients have been mixed in. Also, add some spice - cinnamon and nutmeg for a real taste treat