Hi- sounds like this is rough for all involved. The best lesson I learned in the drop off/pick up exchange is to make it as quick as possible. Make it a happy moment if you can.. Do not prolong the agony or the child's going to feel the anxiety of one or both parents. Both BM & DH need to pump up the positives and learn the fine art of distraction. When SD is on her way home, BM should be all about..."Hi Honey!" Let's get your stuff upstairs, and I want you to tell me what FUN things you did today?
Even if SD just hung out at the house or went to the park. Get the crayons out & let her draw what she did during her visit. (Not saying this to evoke any provocation on either side.) But when SD is on the phone and is crying? DH needs to just calmly say to her, "Hi DD, what's going on? You miss me? I know honey; I miss you too. Hey, can you draw me a picture of you & me?" Or "What are doing right now?" Did you have fun today? Can you draw me a picture of that swing we went on at the park?" And so on...getting my drift?
I've gone through the separation anxiety deal as well with all 3 of my BIOs. The best trick I ever learned was to make the child laugh on the phone if you could. My DD10 was a very alert little girl and we often read books when she was small; so she knew a lot of things, so we would talk about things that made her smile and engaged her into something other than her sadness. You almost have to start new rituals, if you will. So then, its not as painful for BM & DH. I am the BM; and while my heart of hearts was breaking saying good bye to my DD? I had to suck it up and not cry. So, I hope this helps a little; or maybe even a lot.

I was involved in a divorced setting and whenever it came time for my dad to drop me off i would cry and not want him to leave. Don't get me wrong I loved my mom and it wasn't because I didnt want to be with her. But I just needed more from my dad. I dont know how your husband is with his daughter but I was not a high priority once he was remarried. She was only 21 i believe when they remarried *he was 25 so jealous was a huge issue. Bottom line I picked up on it. I agree that it needs to be quick and the more drawn out it is the more the anxiety builds. Regardless, perhaps your DH could talk to his daughter and see why she does it? Maybe she has important needs that aren't being met. Or maybe she is struggling with the separation in general and if thats the case counseling might be an option.