The S word

I am unsure as to how to react to this. Gmom had started calling s stupid. I am not sure of the exact context since she is speaking cantonese, but I think it has to do with s not being able to listen, eat by herself and speak clearly. She says (progressive tense intentional since she has done it more than once) this usually when she is trying to urge g to do something, calling her smart and then comparing her to her one year old sister.

Far be it for me to say that g is not smart which I think she is. I don't think that it is good nor is it a fair comparison. I admit to doing comparisons but usually I contextualize it as g being the big sister needs to help s out on things. Like, "you can pick your toys. s needs help picking up her toys because she is still a baby." or "you can use your words. you have to help s learn words so that she can tell us what she needs."

However it really hurts me to hear her call s stupid for not knowing a word or mispronouncing something, as in she would say "te te" or jie hie (mandarin for big sister). She knows exactly what she is referring to though.

How would you react? I have asked G that if it comes up again that he should tell Gmom that she shouldn't use that word. G doesn't think it's a big deal since that is how he was raised. I don't think I want to raise them like this.