I am not yet in your situation, only 1 DD, but a very wise women has informed me that it is most likely jealousy.

My mother is an early childhood specialist, (lucky me!) and after 40 odd years in the business of kids she is usually right on the money.

Mum explained that jealousy in siblings often rears its head at the 6 month mark after a new baby comes into the family. (Sometimes up to 12 months after). Often, a child who has accepted the new sibling up to that point and had no issues whatsoever, not a hint of jealousy will suddenly realise, 'this kid is not going away'! In addition, the new addition has not really made to much of an impact on their daily life up to that point, lots of newborn sleeping etc, where by 6 months they tend to need a bit more attention and suddenly child #1 has to share your attention more. Apparently your DDs change in behaviour is really quite common if not quite distressing as we tend to expect that the bad behaviour and jealousy will start when the baby comes home.

I am sorry that I don't really have any practical advice relating to what to do, (Mum is asleep now and would not take kindly to recieving a phone call!) but I hope it helps to have an understanding of what MAY be going on.

Maybe you could try some of the things you originally did when your DD2 came home from hospital, involving DD1 in DDs care, using a baby doll for her to act out similar behaviors to you, putting aside time alone with DD1 reguarly so that she gets your undivided attention.... I am sure there are more suggestions, but as I say, I am not up to this delight yet!

Best of luck, I am sure your little angel is right around the corner.