First of all, THANK YOU to everyone who has been following along on this since I'm not bothering to fully recap (it would be way too long of a post then anyway. The advice has been invaluable.

So after talking to FIL about being stood up and the ongoing favoritism, we had agreed they could stop by this weekend and take SD (I had second thoughts on this even at the time). After finding out from SD this morning that they're all in contact with her while shes at BMs also (which means that all the "well we never get to see her or talk to her" is BS PLUS the over the top thing posted online for celebrating her birthday, etc, was just to show favoritism because they actually had already told her in person) I told DH that he should text FIL that actually this weekend wouldnt work.

MIL messaged DH this tonight:

Hi DH, dad told me that you and he had some words in regards to the tensions that exist in our family. He also told me that YDS had a severe allergic reaction. Poor little guy, how scary. Please know how much we love you and that neither dad or I want things to continue the way they're going. There are two sides to every story. We truly are broken hearted and I hope we can sit down and talk about things. I will leave it at that because I don't want to discuss it anymore via messages. PS hope we can get YDS gift to him soon - he cant wear the romper I got him in the winter. 

Just as a side note, one of the things that was discussed in the phone call between FIL and DH was that they were so desperate to get SDs present to her, but weren't concerned about getting YDS to him even though his birthday was the week before. Also, gift giving is the one thing MIL is always very anal about, even to people she dislikes. At times it feels more like a manipulation to me to receive something from her.

Now as a mom, it makes me feel kind of sad to read this. But at the same time, I have doubts that she would have messaged DH about it at all if she had gotten her way and they were going to be getting SD this weekend. I also think the "theres 2 sides to every story" means the discussion will turn into her airing her grievances.