Ok so would a mix of cracked corn and cat food work as the main feed for 1-2 weeks? With fresh fruit and vegetables for snacks and also mealworms and treat squares on the side to as 10% of diet?
I was just going to suggest that
I would not try to mix the corn and the cat food.
Just put them in separate dishes and let the ducks choose how much of each to eat.
And yes, fruits & vegetables are a good idea too.