How to respond without blowing up court case...

[gma29]

Little background:
My son was abusive to his ex - from what I can tell it now appears to have been mutual but that is not probably relevant.  My husband and I were close to his ex and I worked with her to get an OFP because of the documented abuse.  They violated the OFP together (she went to his house, they got in an argument - go figure - and the landlord called the police) and he was charged & convicted and is going through the whole process of dv classes, probation, etc.  They continued to violate the OFP and now a DANCO as well together and she would drop their daughter and her son off at his house all the time for overnights, etc. 

Then she got a new bf (who was also extremely abusive and a thief) and she began talking about moving from MN to TX and taking the kids.  In addition, she and the new bf faked a DANCO/OFP violation by creating instagram messages and placing a knife out alongside her car.  We know she did this because she actually wrote it in her victim impact statement AFTER he'd taken an Alford plea (because the evidence showed he did it and he couldn't prove he didn't and the plea kept him out of prison) and now has a felony dv on his record.

Now to the problem/question:  When she talked about moving, I helped my son with the paperwork to file for custody - knowing that he'd get standard parenting time at best - but we (our whole family) were working to keep her from moving out of MN.  Got it filed, made a mistake on serving and it was closed, but it was enough to make her stay in MN.  Mid July the DANCO was modified to allow text or email messages regarding parenting time for my granddaughter.  The ex is furious with me and my husband for helping our son to file and has said that the only way our granddaughter can be here is if our son is with (we'd had her at least one weekend a month for a year before without a parent) and is jerking him around on time.

He did a new filing for just parenting time with a basic schedule, except that he is asking for (and she'd already agreed) to Thursday through Sunday e/o wkend.  At this point, she hasn't responded to the filing and the only thing that has happened is a proposed order has been added to the case.  No court date yet.  He will be calling on Tuesday to see about why a date hasn't been scheduled.

For this summer, my husband and I have been doing the pickup/dropoffs because of the DANCO, but we don't live in town and won't be in town when he needs us for the next few visits.  He texted his ex to confirm next Thursday through Sunday and she came back with Friday through Sunday.  He said that he's petitioned the court for Thursday through Sunday and that is what he would like to have.  Her response "idc take it or leave it. or take me to court frfr".  Not sure how she doesn't realize he already IS taking her to court (note - 65 page affidavit with 55 pages of text screenshots showing her jerking him around and trying to cause an argument.  He's been amazing at not engaging - I guess a prison sentence hanging over you will do that).

In any case, our fear is if he takes the Friday - Sunday, then that will impact his case for wanting Thursday - Sunday.  But, if he doesn't take it then he loses him time with his daughter and THAT will impact his case for wanting time altogether because she already says that he doesn't want time with his daughter or he wouldn't let us take her on his time.

How should he respond to the "idc take it or leave it" to minimize the negative impact to his parenting time case but also not engage in an argument that could violate the DANCO?