I currently have 2 dogs and want to add a working puppy in the next 6 months. I have some questions about having 3 dogs and my plans to live with them.

Hello, have read your information on keeping dogs seperate and have a question. Some background, I have 2 german shepherds age 9 and 11. I got them in Germany. One is a high line dog and one a working line. Both are well socialized and obedient and have no aggression toward each other or other dogs. They are both trained in schutzhund which I did for 6 years while there. They have always lived together with no issues. I want to get a new working puppy in the next 6 months and I wondered if I should keep him seperated? I would of course keep him seperated until at least 7 months old and I was confident they got along but what about after that? I want him to be a part of the family as the other two dogs stay inside with me they are both crate trained and have inside crates but can go in and out at their leisure because of the dog door. I never even knew until now I should keep the dogs apart and I have had no problems at all. What are your thoughts?