(English below!)これするついでに、とみなさんもすることはありますか?ついでの用事だけを済ませて、はじめにしようとしていたことを忘れてしまったり・・・ You may do a lot of things while you're at it. Sometimes people forget the original purpose and only do the second thing.
what baffles me here is why the other family members are not helping the mom and just watching her, is there a rule that only the mom can and should do the chores?
My family does this to me too. It has reached a point where I no longer disclose what intend to do because family members will simply tag on to my actions.