My 5-year-old sons' behaviour has deteriorated over the last 9 months but mostly in the last 4 months has it been more noticeable.
He will hit and lash out at both myself and my partner's children for no obvious reason. When he does this he is sent to his bed and has to sit there for 5 minutes. Each time he hits (within that day) he is sent to his room and an extra minute is added to the time. I've also punished him by taking away items he likes to play with, trips out having been taken away.
Example of what tends to happen.
My son and the 2 yr old were playing in the garden. The 8 yr old went out and interrupted the game. The 8 yr old was trying to annoy both the other children so I went downstairs to diffuse the situation and make sure the 8 yr old didn't continue to annoy the other children. In the time it took me to get downstairs my son had scratched and hit the 8 yr old.
I was taking my son upstairs (different incident from the one above) as he had been told to get changed for bed an refused. While carrying him through the living room, he slapped the 2 yr old in the face. The 2 yr old had been sitting watching TV for 10 minutes and had not been involved in anyway with what was happening. He had just been within reach at the time.
General shouting and screaming, lots of "I hate you's" to who ever is close by.
Some back ground information.
His mum and me don't live together and he sees her 2 days a week. This has been the case since he was 18 months old.
We have moved in with my partner in February of this year
There are 5 children including my son in the house, age of the children in the house are (2(m), 5(m), 6(f), 8(m) and 10(f))
I'm pretty sure he struggling as he has less 1 on 1 time with me, at the time we moved I was dealing with some other issues that prevented this. That said it isn't that I don't have the time to spend with him, I just don't want to start to give the idea that unwanted behaviour gets extra time with me.
TL;DR
How do I stop my 5-year-old hitting myself and my partners children?
How to reward good behaviour and discourage bad behaviour in 1 child while not appearing to show favouritism or rewarding that child in the eyes of both older and younger step-siblings.