I have one dd already (6) so would have thought I'd have come across this but don't remember it!
DD (15m) goes beserk if her father leaves the room, even if I'm still in the room with her. She screams and screams. If distracted she'll sometimes stop screaming after 3 or 4 minutes but other times she just keeps on 
He's started carrying her all the time, when cooking, tidying, going to the toilet!!
At my parents at the weekend she had the attention of her gran/grandad/me/sister and still screamed the house down when DP went out to the car. She kept it up till 5 minutes later when he came back in and picked her up. The minute he picks her up she stops. If he leaves the room and shes on the floor she crawls after him screaming.
Has anyone else gone through this? She also screams if her sister sits on me when she is also on me, and hits her to try to get her off me. If dd(1) sits on DP dd(2) goes mad.
Interestingly she doesn't scream or get upset when dropped at nursery 3 days a week.