Don’t free feed (leave food down all day). Monitor meals. Feed on opposite sides of the room in separate dishes.
In fact separate the pups with a gate, different rooms at mealtime if you have to.
Most adult dogs do best with 2 meals per day and an occasional snack. At 5 months old the pup should be able to go to 2 meals per day soon if not now.
You are in charge. Do not allow the dog to eat the puppy’s food!
If the dog or puppy refuses to eat, pick up the food after 10 minutes, store covered in the fridg and offer at the next mealtime. Eventually they will eat, as long as they are drinking water it’s okay to skip a meal or two unless there is a medical condition that contradicts this.
Just my opinion, consult your vet if you continue to have concerns.
