Those are great pictures, Konstantin! And, thank you for sharing. From the pictures, he does look very comfortable with you. And, I think you are right that he needs to get to know the other members of your family before he can trust them. As for your son, I know that children make quicker movements and that may be part of the problem, along with his voice being higher (I'm assuming that it is as he is still a child, right?). Maybe if they gave him something he likes every now and then, even if it is just putting it in his cage, would eventually win him over.
And, your parrot is beautiful!