Hi there and thanks for the question
Sorry for the delay in replying. As you may well know Rottweilers can be on the aggressive side if not delt with properly when young. They are great family animals and can be very protective.
First things first i think we need to go over some alpha training issues. Dogs are pack animals in the wild...and should be in the home. Dogs are happy when they know there place, and don't challenge. So for both his and your sake i think it is important to get him knowing he is at the BOTTOM of the pack. This may seem mean but trust me he will thank you for it
1) When he is sleeping in a hallway or doorway make sure to move him out of the way. Stepping over or around him will only lead her to think he is higher in the pack.
2) You should always walk through doorways first. Make your dog sit and wait. You can even walk around the house with him on the lead to reinforce this.
3) He should always eat after everyone else in the household and never get food from the table.
4) When you get back from work or being out leave him alone for 15 minutes. Wait until he is calm and relaxed and then go see him.
The next major thing to go over is obedience. Your boy must be very well behaved so you can trust him whenever where ever. Work with him for 10 minutes a couple of times a day on the commands of sit, stay and come. Keep up the training and you will notice it does help. It is also a good idea to get the kids into training him but only when you are there to make sure things go well.
Next it is very important that you tell him off when he is acting innappropriately. This may be anything from snarling, nipping, growling or biting. No matter how minor or major it is he needs to learn that aggression is not ok.
So when he misbehaves tell him off straight away. Use a loud GRRRR or AHHHH as well as a squirt with a water pistol or throw a blanket over him to stop him. This will give him a fright and make sure he knows he is misbehaving.
I think more socialising and controlled interactions with children will help control things.
I still think the muzzle will be best in these circumstances.
First we will start with people and children and then later move to dogs.
Now we need to introduce him to as many people as possible in your home. He does need to be on a lead and muzzled.
1) Have the person sitting on a couch
2) Have him sitting 5 metres back. When he behaves and sits he gets praise....when he is aggressive he gets told off just like before
3) He can advance a half metre at a time once he is sitting and relaxed. If he growls reprimand him and wait. Keep waiting and reprimanding until he is calm then proceed.
4) Make sure your friend has some treats in there hand that he can take. Avoid sudden movements and loud voices.
You will need to repeat this over and over, with different people etc
With children make sure that you are in control. Avoid telling your children off in front of the dog and make sure they play gentle as many dogs will snap if they are being teased, poked or pulled.
Now you can do the same with dogs in the backyard. Don't let the dogs meet on the first occassion but they can later. Only allow gentle play and no rough housing.
AVoid walking him until this stage. Muzzle when walking. When you see someone coming make him sit. Again he is rewarded for being relaxed and reprimanded for growling etc. If he gets too much you may have to take him away.
But keep being persistent.
If he snaps reprimand her firmly. Be persistent and take things one step at a time. This will take time to fix so keep me informed okay? As long as you tell him off and socialise him i am sure the problems will slowly subside
Todd