Partner wants another dog - How do i persuade him not to?

We already have 7 dogs - 4 rescues and 3 KC reg. We also have 4 children under the age of 7, 4 cats, and other animals including guinea pigs, rabbits, rats, gerbils and a hamster. I DO love dogs but i just think at this moments it's not a good time as i only had our youngest child 3 months ago. He has a habit of being ''spontaneous'' (as he likes to call it) and going out and coming back with dogs. In the last 2 years he's come back with 3 different pups and me being me never says no. I've already told him that we shouldn't get another dog just yet but i have a feeling he's planning on yet another new doggy addition to the ever growing family. India (SBT mix) is 11 years old now and we've been in and out the vets with her ever since we rescued her. Xavi has got it in his head that she doesn't have long left as she is on alot of medication atm. But i think we got a couple more years in her and the vet thinks so too but i think he's trying to ''replace'' her already. He does do most of the things - walk/run with them, feed them, wash them BUT when he's working i have to look after the animals and the children and it does get a bit of a handful with 4 children and 7 dogs - 3 of which are still playful pups. ALL our dogs are well behaved, and we CAN financially afford another one but i just think its not the right time. He is a 34 year old man acting like a spoilt teenager. I just want him to understand no means no. Any tips??