If you are unwilling to butcher the chicks, give them to someone else. Yes, there are those that keep them as pets, but they have to be kept on a reduced diet, and they will likely die young - spontaneous death, heart attacks, and leg issues are common. They simply were not bred to live longer than 8 to 12 weeks. There is also no benefit in keeping the chick longer than that. You may have a rooster, which would be useless to your flock, since it would be too large to breed naturally, and may be so big that it hurts your hens. It would also be too large and slow to be effective as a protector. If you have a hen, they will lay very few eggs.
The chicks were bred to grow fast and be butchered young. It would most likely have a diminished quality of life being kept as a pet. There will be those that say you can keep it, if you restrict it's food. Try it if you must, but be prepared for extra management and possible death. Sorry.
ETA: if you do decide to butcher, you don't want to keep them for another 11 weeks. They'll need to be processed at 8 weeks old. Not only is it better for their health, as they'll start having serious weight related issues after 8 weeks, but they'll also eat you out of house and home. I have 10 meat birds right now that are almost 8 weeks old, and they went through 50 lbs of feed in the last 5 days.
I know it can be hard to detach emotionally - I love all my animals, and raising meat birds was not a decision I made lightly. I have been a vegetarian for 4 years! You can find a butcher that can process them for you, so you don't have to do it yourself. And they will be the healthiest meat you can provide for your family.