Valerie showing her violent side

I know all parents will say their kids are the best, and I'm no exception. I feel overall Valerie is a pretty well-mannered child. She hardly fusses or throw a tantrum (maybe she hasn't reach the terrible two age?). When we say 'no' to something she wanted, she will curl her lips and show she's unhappy for a while and forget about it. Sometimes, when she want something like a balloon or a toy that is not hers, she will point and look at me for approval. Even if I say 'yes', she will not dare to take it, unless I take the toy and give it to her myself. So she has some sort of a boundary control.

But yesterday, while we were at MIL's place for dinner, Valerie was playing at the living room while both of us had our dinner. As usual, grandma would watch over her and her cousin brother who is 5 months younger, she known as 'Didi'. But Didi, always like to walk up to her and snatch her toys. Whatever she is playing. Even if both have exactly the same toy, Didi still like to take hers. When the toy is snatched, she will not dare to take it back from him. Instead, she will curl her lips, and run to grandma and whine, pointing and saying some words that we don't comprehend.

So I supposed this 'unhappiness' must have bottled up in her for a while until yesterday, she finally went forward and hit Didi twice on the face. Didi then tried to do the same to her but his mom step in to stop him. All this while, both of us were at the back washing dishes so we didn't see what happened. When we left later and seated in the car, I tried to talk to her.

Me: Valerie, why did you hit Didi?
Valerie: *start hitting mommy instead*
Me: *I hold her hand* Valerie, you know you can't hit Didi...
Valerie: *start hitting mommy again*
Me: *I hold her hand* Valerie, you can't hit Didi...and stop hitting mommy...
Valerie: *start hitting mommy again*

 
At the mention of Didi, Valerie would start hitting me again. So after a few times of trying to 'discipline' her, I thought what actually led to her behaviour. Then I asked her this 'Valerie, are you angry because Didi took your ball away?'. This time she didn't hit me, instead she hugged me and put her head on my shoulder.

I hugged her back and stroked her back reassuring her it's ok. I guess she must be upset that her toys are always snatched away, that she finally hit him back instead. At that moment, I saw no room for further disciplining and let it go. I then remembered something I read from the Shichida book about the importance of listening to your child. Going down to her level to understand where she is coming from. Have I not done that, I would have just spanked her till she cry and scold her to not repeat the same thing.

When I told nanny the next day, she said I should have given her a good spanking so that she won't repeat this. Well, I understand where she's coming from. But I don't feel spanking her would have solved anything. Perhaps if she repeat hitting Didi again, I may have to do so.