Ill give a brief outline of each dog so you know how many we have etc.

1. Male Labrador (Entire) 10 years
2. Female Malinois (Entire) 7.5 years
3. Male Malinois (Neutered) 8 years
4. Female Dutch Shepherd (Neutered) 6 years
5. Male Malinois (Entire) 3 years
6. Female Malinois (Entire) 15 weeks

My Labrador generally does not interact with any of the dogs except for bitch 2. (At one point there was just the 2 of them). These days he only tends to bother with her around the build up to her season where he washes her face and ears for as long as she will let him.

She has a season which finished about 2-3 weeks ago, in the build up to her season he washed her like he normally would and a bit while it was going on and then stopped (nothing unusual)
The strange thing is he has started to do the exact same washing of my youngest male (dog number 5). It started mid way through the bitches season but didn't ever stop, my youngest is quite happy to let him do it but it goes on for ages and he ends up absolutely soaking wet (and smelling of dog slobber)

Any idea on why he has switched his attention to my boy? If i spot him doing i i have been tending to put them in separate rooms until the older one falls asleep. Neither male is particularly dominant, Bitch 2 is the most dominant one of them all.