IMO it is not your job or responsibiltiy to make your mom or sister happy. it is your job to make you and your kids happy. post as many pictures as you want, if they want to seek them out, that is their job. christmas, birthdays, easter, mothers day...whenever you send a card, that is when you send pictures of your kids........she is their grandmother. it is your job to send pics a few times a year at least to keep her updated on their growth. but quit feeling guilty. you moved away from home so you wouldnt have to feel that didnt you?
if you want to feel closer send more. better yet...leave it up to the kids.....have them write letters once a month with pictures to send.
but i am a bad example...i disowned my family...lol