Don't be unhappy la. The relationship of daughter vs daugther-in-law is very different. Your mum also treat you much better than your C6 la. This is logic ma.
Don't be silly. We are different to 99's own daughter. But at least your 99 is just normal. My 99 is even worse, she came to help her own daughter (which is, of course, expected) and my sister-in-law, but not me.
My sister-in-law has a lot of gifts and good food, me? nothing ar !