I feel for you and know what you're talking about. I have an older dog of 8 years. He lives in our yard because he is way too big to come into our home. He basically only barks when there is a dog, cat, or person in our river. Normally, he is very quiet. However, at night he does seem to bark more because the cats around us seem to fight a lot. Then we have the 5 little ones who live in the house, they range from 5 years old down to 1 year old. They are the barkers. I have one who is the puppy of the 2 of my dogs and I can't seem to get him to stop barking. When he starts the others seem to follow. Here are a few suggestions of what I have done to control the barking of my dogs and this seems to really help at night to keep them quiet when everyone is sleeping.
I had to lock the dogs in a room by themselves and put their toys in the room for them to play. They are Bichon Frise and they love to play for sure. I basically need to keep the little dog's father in my room at night along with one of the smaller ones. This keeps them apart. I've never had an issue with the father, but the mother loves to bark. She normally will stay with me too. I put the 3 puppies in a room and put the tools in the room for them to play with. This keeps them busy at night and they don't go barking and making a mess.
I have a broom that is made out of the coconut leaves that I use to scare them with. I don't hit my dogs all I need to do is pick it up and show it to them and they stop barking. I think you need to find something that they are afraid of when they see it. Like a rolled up newspaper that you can hit on your hand. When they start barking pick this up and hit it on your hand. They will get scared of the sound and run. This was the best way I found to keep them from barking all the time. Just the noise of my broom keeps them quiet. I basically just tap it on the floor and tell them to shut up. They hear this and are quiet.