When I picked up Em tonight from Helen's, I discovered Em now has a new friend called Ellie.
She's a bit younger than Em and apparently Em is "showing her the ropes" - how to read books, how to sing nursery rhymes, etc. She's only 2.5 and not really old enough to be the older child (that's around 7-8 I'd reckon) but it's fun to hear about Em being the "grown up" showing Ellie the ropes.
I get it foreshadows how she'll react to a sibling when he/she eventually arrives.