I've learned the hard way, from experience that you can't have two unaltered males together. They do compete for the female dog and for attention.. Thats why they only do it when you are around. Most likely they all need to be spayed/neutered to get along.
also you need to let them know that you are the alpha.
One thing I find helpful is an empty clean & dry alluminum soda can.. Put a few pennies in it and tape the hole shut.. Shake this can if any start exhibiting an alpha behaviour and use a command word following the shake.
I know how horrible it is to separate fighting yorkies. Its nearly impossible.
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