My niece is like a daughter to me and I help take care of here whenever her Mum is doing errands.

Lately, though, I noticed that she's starting to learn how to fib and she can barely speak straight! This concerns me since she's not my daughter but I want to make sure that she doesn't do it again.

Do you have an advise to an aunt who would like to cut that bad habit from her without stepping on her Mum's toes?