close siblings: how to manage separation anxiety from each other?

[Greythorne]

We have two DDs aged 4.3 and 2.2. They are close and love playing together. They share a room (small house) and it just evolved that they now sleep in the same double bed (a sort of continuation of co-sleeping, they choose to sleep in the same bed). The sometimes sit on the same (Tripp Trapp style) high chair to eat meals. They often share cups of juice.

They are really, really close!

Which is lovely most of the time, but when DD1 is at nursery, DD2 gets really down, wails and weeps for her big sister, calls her name out (as if looking for her) and gets very agitated when I expalin that her big sister will not be home until X time.

Any ideas how to manage this?

Can you think of some activities for DD2 to do while her sister's at nursery?
You can emphasise the fact that her time at home with you is 'mummy time' and that she gets extra good points that her sister misses out on by going out. She is probably not only missing her sister, but is also jealous that her sister gets to go somewhere as exciting as nursery.
How about some crafts, cooking or gardening? Or maybe some extra play dates with her friends?
I'm sure you can think if plenty of things to fill her days and distract her from missing her sister.