Some of you may have saw my previous post (deleted) about Dh's work schedule changing.
Long story short: CO states he gets two weekends a month and 3 on months with 5 weekends. He's to let BM know his weekends 30 days in advance. Also, if there are any changes, he's to let her know 30 days in advance.

His schedule at work unexpectedly changed. Because his schedule is so predictable we created a calendar for BM a year in advance of his weekends to make things easier. We didn't want to have to talk to her every 30 days and discuss weekends. Even though TECHNICALLY that's the way DH can do it per CO.

DH contacted BM about the change and BM flipped out saying no. She has plans already for all of her weekends for the rest of the year. (bullshit).
She accused DH of lying, wanting to steal her weekends, and being a POS father. She demanded for proof of his schedule change from his job. (just like how she demanded for proof he took vacation during his summer weeks - we already had that fight with her and told her no, so I don't know why she thought it was okay to keep demanding proof of things.
DH explained the CO to her, stating he doesn't have to show proof, she will just have to trust him and work with him. He works, she doesn't. Things happen, things change. DH doesn't have any more control over his schedule as BM does. He stuck to the CO, stated he was in compliance. Reminded her that he DIDN'T have to make the calendar and did so to make things easier. Repeat CO again. Explained that if she wasn't willing to change it, then he wouldn't see his daughter because he would be working the weekends SD is here. I would have to watch her then (nope). etc..etc...

She wouldn't budge. She pretty much told DH that she's not changing anything unless she has proof. She said something like "yes, the CO says you don't have to show proof, but it doesn't say you don't have to either". She would twist words in the CO or imply that just because the CO doesn't mention he HAS to do something, doesn't mean that he DOESN'T have to.
She even stated that some things in the CO don't apply to her because she has SD more. "don't like it, file for a modification then" - she said.

uh NO! Not the way it works.

DH had the final blow. He was stern. Repeated the CO and told her how he was in compliance. That if he needed to file for ANYTHING, it would be for contempt of not following the CO and of primary custody of SD.
He mentioned the stacks of contempt she already has, the things she's lied about and said, even what she said about how she doesn't need to follow it. The way she acts at exchanges and all the other emails of her being crazy. Not to mention the things SD says about what goes on in their home.
Sooo yeah. You can follow the CO, or DH will be taking the action listed above.
He said he will send her his new schedule 30 days in advance and no longer for now on (because that's how it is in the CO). He told her he was still in compliance and that if SD has plans come up with friends or school, then she can let him know in advance and he will have no problem making adjustments.

She didn't answer after that.

I was working on the calendar and DH told me he talked to MIL about it and MIL said we should send a certified letter from his job about his schedule change. I was so annoyed. I can't stand MIL sometimes and told DH that wasn't necessary. Just because she's his mother doesn't mean she knows all.
What would that DO!? Give BM exactly what she wanted. WHY WOULD WE DO THAT, WHEN WE DON'T HAVE TO....ESPECIALLY AFTER ALREADYYYYYYY TELLING HER NOOOOOOOO. What is that teaching BM? What was the point of stressing the CO to her if we are just going to shrivel at her every demand like MIL does.
WTF!?

We don't need to show proof and we already stressed that to BM.
and guess what...I was right, and apparently BM figured it out.

I finished the calendar last night (I do the calendar part because DH isn't as organized as me and would mess it up).
I gave it to DH and explained where the "30 days in advance" started. So anything from yesterday - 30 days can stay as she already has it. Then after that starts his new schedule.

He sent it to her and said:
"30 days from today is October 21st. So, from today to October 21st, the schedule can stay as you currently have it, unless you are willing to change it to my new schedule. If that is the case, let me know. Otherwise, it's not a big deal and I can work around it if you already have plans.
From October 21st and further, will start my new visitation schedule. I will be sending you a new calendar with the dates in advance, because I really do not want to have to communicate every 30 days about my time. If I am going to do this, I just hope that in the future, you can be a little more reasonable and open to unexpected changes without making demands or accusing me of lying. If there are any future changes, I will notify you appropriately. In the meantime, i hope that we can still work together when it comes to minor things - like we have been in the past. To get you started, my first NEW weekends will be (blah blah blah). I will email you the calendar later tonight. Thank you."

BM said:

"That's fine. Thank you for acknowledging my concern by letting me know a little more in advance than 30 days. It will be no problem working with you in the future. Again thank you so much. And I am willing to work with you around your schedule. I do feel it is important for SD to see you on your days off. I will let you know in advance if there are any changes that I may need. If you have any changes in the future, just let me know. It's no problem. Thank you"

THREE THANK YOUS IN ONE?
I know BM is just trying to stay on her toes about DH's threats. But...it looks like she's working with us. Either because she woke up with rationality that morning or she realizes she just needs to do what is right and follow the CO, or she realized that DH wasn't playing about taking primary custody. And SD has mentioned here wanting to live with us so maybe she's mentioned it to BM and BM is seeing that it could become a reality.

and MIL said to give her what she wants....fuck that.