1 First of all, in front of your little sister, you should say that your mother is worried about her and that she is crying and sad. In front of mother, you should say that little sister is good, the baby's advantages, her progress, her regret and self-blame.
You seem to have mentioned that little sister is good at everything except lying. Why did you lie? Have you analyzed it? It is possible for a child of 1 1 to be afraid of being accused.
3, don't give the little sister qualitative, praise and encourage when you see the little sister. Said little sister doesn't like to lie, sensible, grew up, said every day, said her strengths, don't mention shortcomings, in front of her.