4 years old child

Hello Doctor.
I live with my girlfriend and her 4 years old child inside the house of her parents for the last 5 months.
Up until 5 months ago the child was only with her grandmother for 16 months because my girlfriend was working far away and so my girlfriend came back home 9 months ago.
The childs father was nerver realy in the picture acting like a father for his reasons.
So for the last 5 months since i have enteard to this small packege (my girlfriend me and the child) we have been trying to give the child a form of family. for the 16 months that the grandmother was with the child she was acting more or less like a babysiter and didnt realy give a lot of disiplint to the child.
I know its a little bit complicated but for now we need to stay inside the house of the grandparents witch dont give us a lot of space because they interfere with our effort to give the child the right displine.
My question is that for the past 5 months that i am here we have been seen that the child is speaking with her self mostly when we are angry with her shes speaking only when we are not next to her.
Is it normal?  
By the way when we ask her who was she speaking with she says that with nobody.

Thank you very much.

[RockRose]

This isn't a doctor moderated forum - so if you are seeing a doctor's advice you'll need to post under one of those.

Boyfriends of the mother are notorious for trying to discipline children that aren't their own,  and thinking no one disciplines the child enough.  

Grandparents who came in and rescued this child so the mother could go - somewhere or other to work - are trying their best to do what is best and give this beloved grandchild a good,  stable and loving home,  even if they have to put up with their daughter and now her live-in boyfriend who can't provide for themselves.

And on top of that,  the live-in boyfriend is harsh and now the child won't speak in their presence.

I just thought I'd give you the perspective of the grandparents,  who you are living off.