Hama beads are very good. You can get large ones or the usual ones. The mum can then make a positive experience of ironing them to make something (maybe as a present for grandma)
http://www.argos.co.u...searchtext%3EHAMA.htm
Unfortunately, I think that nothing will really distract your grandaughter from the attention the new baby is getting instead of her. In my, albeit limited, experience, you should be grateful that she is not a boy! My son completely ignored my daughter and proceeded to get up to all sorts of mischief whenever I sat to feed my daughter. My friends who had daughters found that they would be a proper little mothers.