French Bulldog- sudden aggressive tendencies

Hi there,
I am having a current issue with one of my Frenchies. My household consists of a Pekingese, 2 Frenchies, a 13 year old and a 10 year old. My boyfriend is frequently here too.

Isaak, my 2.5 year old Frenchie was added to our family in July 2014. He came from a breeder who chose not to breed him because he is a mighty 32lbs. She decided to sell him (neutered) after she noticed he was being picked on by the other male bulldogs, and despite his size he was super submissive and gentle.
This turned out perfect for my family. Laine, my female spayed Frenchie, is super bossy (yet quite nice all at the same time). Deus, the pekingese, is a super bright guy who just kinda hangs around as a wallflower but is super attached to me.

Now, Isaak at first was very timid of everyone but super friendly and livable, just not dominant in the slightest. Seemed to know he has some weight behind him (literally) and in a really passive way (used his heavier weight) just didn't budge if Laine was after him about some toy or food. In that, he wouldn't growl snap or bark he just simply wouldn't move out of her way. Issak is very nervous on walks- shy to a stranger walking by (avoids them by walking to my other side or out right stops), however if Laine is with him you can see he follows her lead and just sticks with her.

So now to my issue. Recently- as in the last month, if my boyfriend touches sits with me, or Deus comes to sit on me Isaak growls and will snap. If one of the kids comes over to pet Laine, again he will growl, get up and come over to tell them to bug off with a growl. My daughter who is 13 has always been really dominant over the dogs and suddenly even her confidence doesn't phase Isaak. Note though the submissive walks are still the norm- he's his old self- kind, submissive and gentle. Now when my kids bring their friends over Isaak runs to great them by barking or growling. Previously he was happy, friendly and submissive to guests. Interestingly the breeder had never heard him bark in the 2 years she had him!

Nothing changed in our family "pack" other than his confidence (?- it increased). I have never had him growl at me and the moment there is a growl when someone sits down beside me for ex. I immediately pick him up, place him on the ground tell him "no, bad" and ignore him- disallowing him up on the couch for ex.

Now, I don't even have to be in the equation for him to show the behaviour. As in I can be at work and all the same things will happen- guests, attention to Laine etc. I feel like everything points to territorial behaviour over me, Laine and the house and I do not want this to reach out to him becoming like this in walks eventually too. I have made it clear to everyone in the house they have to do what I do- the "no, bad" and ignore- keep it simple but powerful. But my 10 year old and my boyfriend are very timid, like I can tell they are fearful of a snap so for sure Isaak can. Isaak use to love my daughters dad. So when he would come to pick them up he'd run to the door to greet and receive pets. Now he runs, jumps, growls and tries to bite and this happened what feels like overnight. Isaak has "crazy eyes" when he clicks into this mode too, very obvious to me when he is about to get his wires crossed.

I am lost on how to establish pecking order in an environment where a visitor isn't going to be able to just do this- like my family can work on it with individual dominance but Isaak needs to just not be this way and I am lost on how to change him and re-establish his role here. Does anyone have suggestions on how to make a dog have better judgement over his territorial decisions? I think individually I have the right idea but to correct the heart of the issue he needs to understand whether I'm here or not his growling and snapping is not acceptable.

Thanks!

Thanks for including so much information. It is good he is already neutered, I do not think you need to establish a "pecking order" as much as train him that HE is not in charge, the humans of the house are. How much and what kind of training have you done with him? How much do the kids and boyfriend interact with Isaak? Who feeds, walks, etc?

Has something changed with the dog? Have you had him checked by a vet to see if there are any health problems? If no to the first two questions it may be time for training for you and the dog. Do you have a professional trainer in your area? If not, I would suggestion you taking the time to learn how to train this dog properly. Sounds like he could be a good dog if he is trained properly. You should take action before someone gets bite and that can lead to more problems. Good luck.