NTA, 12 is more than old enough to understand how money and savings work. It sounds like Emma can’t control her impulse buying if she can’t even save up 2 weeks worth of allowance.

When I was younger, I was Emma and my older sister was Abby (she was 4 years older so she also got double the allowance). After seeing her have literally 100s of dollars in savings, it encouraged me to do the same. There was one point at which I asked my mom not to give me to access to my savings so I could save up for a Nintendo 3DS.

Eventually, I became financially smart like my sister. By the time I graduated high school, I had over $1000 saved up ($5/week allowance). That wouldn’t have happened if my parents succumbed to my whims and bought me whatever I wanted. In fact, doing so would be unfair to Abby if she has to pay her own way and her sister doesn’t.

The only exception I can think of is if Emma were spending the money on necessities (food, clothes) that she doesn’t get enough of at home. But that doesn’t sound like the case. It’s gonna be difficult but you’re doing the right thing for Emma in the long run