is this abuse?

hi i know a guy who has 3 kids one of them is dissabled and when ever something happens in the house ie the kids are in trouble he isolated his dissabled daughter and make her tell on the other 2 boys. then she get rewarded and the 2 boys get in trouble. is this abuse? and if so what type and what are the consiquences for the 3 kids in the future?

Mostly I would say it's an abuse of parental power. Possibly emotional abuse.

He is setting up a lot of resentment and anger in the siblings which will no doubt spill out later on. The boys will resent her for always telling on them and also for her receiving special treatment (the reward for telling). It might not be seen as special treatment in the father's eyes, but it will be by the boys.

With the daughter, she may well develop resentment toward her father for putting her in this situation and for exploiting her disability.

The father will end up with no respect from any of his children because he is not showing respect for them now.

Maybe nothing if do this way wih each one towards the others. Otherwise is a very despicable way to act. Anyway never putting sibling one against the other.
Its father's task to see and understand the behaviour of their sons.
And the handicapped one need more integration instead of less to help the childish father.