Many congratulations jolly, overly news 
jolly - I would try putting your dh and both the dd's in the bath, under the pretence of you would really like dd1 to be a helpful big sister and help bath her little sister. If that doesnt work, like Ali said, step away from the situation and it will probably remedy itself.
Somehow you do just cope with more than 1, it all just seems to work out. I should think that in the early years it is also easier having a bigger gap as the older sibling can help. And even though every baby is different, it really is easier the more times you do it. I think you become more relaxed and accepting.
The gro clock worked (and still does) with ds2, but I'm sure he was older when we introduced it, maybe 2.5-3yo?
We've had my niece and nephew staying for the past three days. My niece has bathed the boys and got up with them in the morning, and my nephew has put ds3 down for naps. I'm trying to train them for childcare cover during the school holidays for when I eventually go bak to work 