Again, thanks to everyone for giving their perspective. This is a really confusing time for me - this whole thing is bothering me A LOT, and by virtue of my position as the step parent, I feel frustrated that I cannot due more. The following I wrote more for myself, it's just my perspective on things, I'm not trying to make a case for anything, accuse their mom of anything, it's just an epiphany I had earlier.
My gut is telling me that something is wrong. My older SD has had issues with leaving her mom for a while…off and on. I think it started when we told the girls that we were expecting DD3. OSD was ok initially, but later had a moment when her younger sister commented that a horse in a coloring book looked like "it had a baby in it's tummy". After that, during Labor Day weekend 05, we went to a joint b-day party for OSD and for some reason she was unaware that the plan was for her to come home with DH and I. So she freaked, and DH and his former wife deceided that she would stay home, and the ex and OSD would come up the next day and we would all attend the Scottish Games the next day. The visit was fine, all seemed ok.
Then their mom, later that year started seeing someone (around Nov) and by the spring they were moving to another state (alothough only about 40 min away from their old house and 2hrs away from us) and that's when she really started having a tough time. She would cry hysterically at exchange time about 50% of the time. But then, her mom encouraged her to go anyway. This was also a time when visitation with the girls was a lot more liberal than usual. We were being called a lot to see if we wanted the girls for some "extra" time. When it finally came time for the move, DH and mom got together, because apparently since it was out of state, DH needed to be aware and be ok with the move. My gut told me that something wasn't right - OSD was having a tough time, and the move would take her away from her grandparents (her mother's parents), girl scouts, their school, dance etc., and the school year was almost done (it was March) - maybe they could move in the summer, after OSD finished up the year. It bothered me that mom told us that OSD "was fine" all the time, when it was obvious that she wasn't. BTW-- the younger SD seemed like she was just going with the flow.
After DD3 was born, things seemed to be ok for a little bit. Occasionally, there were weekends that she would want to call her mom, but it was hit or miss. Drop off seemed to go ok.
Then there was the haircut issue. DH took the SD's for a trim (really, it was a trim) and their mom was really angry with DH. She called him nearly every day for two weeks about it., and about a month later I was doing OSD hair in a braid and I said something like "you're hair is so long and pretty" (because it is!) and she started crying and told me that she was not allowed to get her hair cut or her ears pierced unless her mother was there.
Then it was quiet again for a while. Last Oct/Nov their mom sent an email about OSD not wanting to come. At pick up she had a hard time again, but once she got to our house all went well. Funny, it was a particularly good weekend. Then we got the email, and the reasons that OSD told her mother that she didn’t want to come was because she had to share a bed (which wasn't true) and that my ODD snapped at her (which was true, but something that was resolved by DH and I), and that she wanted more time alone with her father (which we thought was happening, but no big deal, we made it so that there was more time). Everyone talked, DH made a plan to call every Wednesday eve, and everything went well thru the holidays. Then came this weekend, and its just weird.
I don't know if OSD just has a hard time with transition, or separation anxiety, or what. She has said that she wishes her parents were still together a while ago. I don't think or know that there is one cause, but maybe a bunch of things adding together?
Sorry this is long. DH talked to their mom, and everyone's emotions were running a little high, but at the end, they resolved to look into counseling for the girls, esp OSD. The funny thing is after all this their mom told DH that the girls are "really excited" to come see him this weekend! She said that the girls don't have a specific reason for not wanting to come, or at least haven't given her one. So everything just feels in limbo. I'm frustrated with DH - maybe he could have put in more effort, or I wish that both of them could see the problem that was happening a few years back, and maybe addressed it then. I'm frustrated with myself, because maybe I should have said something earlier, but it's just so weird being the stepmother, and their mom and I have periods of getting along with periods of just not talking to each other.