If you choose an all life stages food you can feed it to the puppy, too. If you choose to feed puppy food I wouldn't do large breed puppy, boxers are considered medium sized.
How much are you feeding? Are you sticking to the feeding guidelines recommended by the manufacturer? They tend to be a little on the high side. If you think overfeeding might be a problem you could try cutting back the food a little and see if that helps. Monitor your dogs in terms of weight, you obviously still want to see weight gain, especially with the puppy.
Santina, owned by
Sky, Boxer, flashy fawn, docked and floppy, 7-24-09, CGC.
Happy, Puggle, 2-28-08, CGC.