My older dog is fear aggressive with strangers and he is aggressive over territory(the couch and the bed and treats) with my SO. He has bitten my SO several times, without growling or barking to warn, but he's never drawn blood. It hurts my SO's feelings more than anything
I am SOOO very careful with him around strangers. I do not let anyone approach him or try to pet him without warning them about him being afraid of people and possibly biting...and I have one friend who brings her child over and she is well aware of the situation and we both watch them together. Luckily Princeton stays away and isn't just going after people. He's afraid of them and while he's curious and may sniff, he'd prefer they don't touch him so he mostly stays away ....but if he were cornered, he'd do the same thing.
I know I am responsible for my dog...not just to keep people safe from him, but to keep HIM SAFE from them. I am ALWAYS on high alert when we are out of our house and other people are around. If it were me, I would definitely be teaching my grandkids "no touch" with the aggressive dog...and I would even consider locking the dog up in a crate in a quiet room, while the grandkids are there.
One of the things I tried was letting strangers be the "bringer of good things"...which was treats!! It may have helped a little as he did get brave enough to go up and take the treat out of their hand, but he still doesn't want them to touch him.
It was really embarrassing to me at first to say "my dog bites"...but now it comes off my tongue like nothing.