I don't think there's anything wrong with having one for dd2 but she probably won't understand the concept until she's a bit older. Maybe just a piece of paper on the fridge that she can put her stickers on when A gets hers would be enough for Z.

I get ya. Maybe just do up a star chart with no list and every time she does something you think deserves a star (like putting a toy back, feeding fish, helpind with the dishes etc) you can make a big deal of and give her a star. That way she'll associate doing things with getting the stars as opposed to you expecting her to do certain jobs. You can have a reward system in place so that when she gets a certain amount of stars you'll take her out for ice cream or do something fun to celebrate.