Darn it! Is it possible to get a puppy (Archie) to stop chewing on the other poo's (Chula's) ears?

They love to wrestle, and Archie loves to pull on Chula's ears. Because of this, her ears are a MESS!! We just got out all the clumpy matts that little maniac put in there.
I asked the groomer for ideas, and she suggested making a paste with "Alum" and putting it on Chula's ears. Heather said that Archie won't like the taste at all. So I picked up some Alum and just now put it on Chupey's ears.
Guess what.
HE LIKES IT!!!
He's standing there LICKING her ear hair!!!
ARGHHHHHH!!!!
Help! Does anyone have any good ideas?