Is it worth it to say anything to her about this? Or is it better to disengage from her completely & cut the toxicity from your life? I agree your SO should have a conversation with his mother about how destructive she’s being & how it affects your family, I’m just not sure it will make a difference. If my MIL was treating my kid this way I wouldn’t want her anywhere around us. 

I'm probably not the best person to give advice on MIL problems, as I went no contact with mine in April 2018.  DH was no contact for a good 18 mths, now has minimal email contact only with her.  Is there a reason why your MIL does this?  I agree that in your place I'd want DH to say something to her - but there's no reason why you shouldn't do this yourself.  

My MIL is not on my social media and I don't even have her phone number saved in my phone.  I dont intend on going to her house for future holidays. 

Your partner can talk to his mom about why she ignores your DD but you might just need to accept that she doesn't want to play a role with your partner's new family additions. Stop tagging her in pics or posting them to her wall.  

I'd imagine that your FMIL wishes things would go back to the way they were, that her son was still with BM.  Does she talk about how awful divorce is?  

If she doesn't want to move forward with the changes in life then leave her behind in the past.

Please understand that I'm asking this respectfully, but why do you care about anything she does?  Does she live nearby whete you can't help interacting?  Is your DH particularly close to her?  Is she the only older mother figure in the family?  Does she have a certain status or weath?  Is she the owner of a family business?  Is she the main influencer of other siblings?

Saying something only backfired in our situation, you cannot cure crazy.  DH deals with all ILs.  We rarely visit, once a year max, and they no longer visit unless it's to see SD & BM, which is less than once a year.  All the kids are lucky to have my mom, who is an AMAZING, fair, loving GM regardless of parentage, and just a great example of a good human being all around.

I'm curious how things that you post are deleted?

I know that the Fbook "stories" expire and go away.. and sometimes Fbook is funny about what it shows you.  I commented on a post in a group I belong to the other day and I never saw any notifications of further responses.. and there were some.. so social media can be weird.

My advice is to not "care" about people that don't care about you.  I would take them and their actions at their absolute face value.  If they show interest in your DD.. be pleasant and neutral.. if they don't.. I wouldn't care anyway.. the important thing is your DD has two parents who love and support her.. period.  Extended family is often more of a curse than a blessing.

I recently read an advice column where a woman was lamenting the loss of her mother the "typical involved grandma".. and that she was so dissapointed her husband's mother wasn't "stepping up to the plate" like she wanted her to.  Not everyone is going to fit the role you want them to.. you can't make distant granny be grandma bakes you cookies if that isn't in her makeup. if there is conflict under current with your relationship with your MIL.. that could also impact her relationship with any of your bio kids... 

I would just stop expecting as much from her.. that way you won't be disappointed.