What a a sweet and throughtful idea, I have no doubt that your mom and your wife feel extremely lucky to have you :)

One of the (many) great things I learned from my mom was the importance of sibling bonds. Tattling was strongly discouraged in our house unless it had to do with endangering ourselves or others, and if we got into an argument we had to resolve it before bedtime with hugs and 'I love you's. This practice led to us being not only close siblings but best friends.
I've continued this legacy with my own children, who at 13 (Ethan) and 16 (Zoe) are also the best of friends, I'm proud to say.
I will definitely let my mom kn,ow I told this story, she'll be thrilled :)