Thank you Mermaid.
I've just seen that the boys have another sister, who is four. That must mean that their mother became pregnant very quickly after leaving, or was perhaps pregnant when she left.
That must add to any feelings of confusion he might have, if she left him and his brother and immediately had another baby who lives with her full time.
OP your description of his repeated behaviour, getting in her face so to speak, reminded me of the description of schema behaviour in younger children. You know, how they will repeat something over and over, like dropping their cup from the highchair so you pick it up and they drop it again. Apparently it's all a part of their development, they are learning something by consistently repeating an action or pattern. And in those situations, repeatedly dropping a cup or, like your DD, knocking down a tower, they are a good thing.
But I've read that they can also develop from upsetting early childhood experiences, such as 'abandonment' by a parent. And they can come out as a pattern of repeated 'bad' behaviour that creates a bad situation rather than a good one, because in a way that bad situation is comforting for the child, it's what they know so it's how they cope.
I can't find the article I was looking for but this one is quite interesting too.
This passage stood out to me as perhaps being relevant to your DSS.
What type of early childhood experiences lead to the acquisition of schemas?
1 The child who does not get his/her core needs met. The child needed affection, empathy and guidance but didn?t get it etc.
2 The child who is traumatised or victimised by a very domineering, abusive, or highly critical parent.
3 The child who learns primarily by internalising the parent?s voice. Every child internalises or identifies with both parents and absorbs certain characteristics of both parents, so when the child internalises the punitive punishing voice of the parent and absorbs the characteristics they become schemas.
4 The child who receives too much of a good thing. The child who is overprotected, overindulged or given an excessive degree of freedom and autonomy without any limits being set.
Therefore Early Maladaptive Schemas began with something that was done to us by our families or by other children, which damaged us in some way. We might have been abandoned, criticised, overprotected, emotionally or physically abused, excluded or deprived and, consequently, the schema becomes part of us.
Schemata are essentially valid representations of early childhood experiences, and serve as templates for processing and defining later behaviours, thoughts, feelings and relationships with others. Early maladaptive schemas include entrenched patterns of distorted thinking, disruptive emotions and dysfunctional behaviours. These schemata become fixed when they are reinforced and/or modelled by parents.
Long after we leave the home we grew up in, we continue to create situations in which we are mistreated, ignored, put down or controlled and in which we fail to reach our desired goals.
Schemata are perpetuated throughout one?s lifetime and become activated under conditions relevant to that particular schema.
This is what the description of him repeating behaviour he is constantly told to stop reminded me of. Maybe he can't stop, because it's become his way of expressing his insecurities about his mother leaving and the two new sisters who haven't been 'abandoned' by their mothers in the way he was.