this is easy. there is a rule for this. no touch no talk no i contact. when your dogs start acting like that don't touch them, don't talk to them (that means no yelling), and no eye contact. completely ignore them. when they stop barking give them a reward even a pet will work
I'd suggest reading "the Other End of the Leash" by Patricia McConnell, or her other book "For the Love of A Dog" or both! They are both amazing books. They really helped me understand the differences between the way humans relate to each other (hugging, touching a lot of the time, kissing) and the way dogs relate to each other.
This dog is probably just feeling threatened by their behavior and so he starts freaking out about it.
I really suggest those books, my favorite part about them is how unbiased McConnell is. She doesn't try to force you into a specific way of training your dog, she just lays out what's going on in the dog's head and gives you tips on how to change your behavior to be more dog friendly. She's also really funny which is a huge plus! =D
Edit: I kinda misread your post. =/ I still recommend those books though!
Another idea is:
Have they tried crate training this dog? It might help said dog be more comfortable if they put the dog in the crate and went in a different room to kiss...And then slowly phased in kissing in the dog's presence while the dog is in the crate...