How to get cooperation from uncooperative MIL?

First of all, you two are not responsible for her. Unless the two of you named her conservators/guardians, you are not responsible for her. She is responsible for herself.
I've been an in-home caregivier for almost 25 years. I have told many, many elders who were suffering from ESS (Extra Stubborn Syndrome) with an underlining case of stupidity that there's no better and faster way to get themselves a one-way ticket to a nursing home than an acute case of ESS.
So you tell your MIL this.
Assisted Living would be better for her physically and mentally. Don't worry about memry care being needed down the line. There are AL facilities that also have a locked memory care facility.
Leave her to her own devices. That's not cruelty. It's tough love and your MIL is in serious need of some. Going on your vacation is the best thing you could do for her. Many elders have to learn the hard way that their stubbornness will not be tolerated from their families and no one will be playing their games.
If your MIL wants help from you and her son then you will help her but it will be on your terms, not hers. If she means to control your lives through her 'stubbornness' and thinks everyone will dance like puppets while she holds the strings, she is mistaken.
Make your language plain when explaining this to her so that she doesn't misunderstannd. Then go on your vacation. Don't play her game.

You described my mother and our situation for several years. I pushed her into respite care so I could have a break and get my knee fixed. Packed her bag and put her in the car. At that point she was so angry and so demanding and so criticizing, blaming and shaming, I figured I had nothing to lose.

What have you got to lose?

Turned out my mother showtimed for the staff. Her rage and rudeness were all for me.

I knew she was slipping cognitively, and was shocked when her assessment revealed that she couldn’t name the town in which she’d lived for almost 20 years. She didn’t know her age or date of birth. She thought her parents were alive.

She is now in permanent care, as of spring 2022, and is content there.

You may find your MIL is already at the stage for MC.

Save yourselves. Don’t wait.

Margie, you and your husband get to decide whether or not you go away for ten days.

Your MIL gets to decide whether or not she stays in respite care while you're away.

You see the difference? You and DH are responsible for what you do. MIL is responsible for what she does. The error lies in believing that DH is responsible for her choices. He isn't.

You already have a system in place to catch any emergencies. Check she has all the supplies she'll need for those ten days - medications, groceries, disposables - and off you go.

I left my live in fiancé mamas boy last week because he devotes most of our time to his mother who will not accept care in her home, can’t do a thing for herself and she refuses to go to a home where she should be. I’m so angry and disappointed that he actually said I’m not the fiancé for him because I wouldn’t move in to care for his selfish miserable stubborn mother who never thanks just orders us around. So glad to be away from them both!

I would not give her a choice. Her doctor agrees she should do it. I would tell her that you r going on this trip and she has no choice because she cannot be left alone that long.

Maybe while ur away, she may find she likes the AL.

Some people on this forum have employed "therapeutic fibs" to get their uncooperative or fearful LOs into facility care. You seem to think that your MIL still is very mentally "functional" but I beg to differ. Just being a refusenik doesn't make her lucid. Stubbornness is a hallmark of dementia.

She is probably beyond AL but not quite ready to MC or LTC, since she is still mobile but a very high fall risk. I think the back-up plan for your son to call 911 if she falls or has a problem is what I would do. Make sure your son knows to not pick her up -- call 911 even if she doesn't seem injured or insists she isn't hurt. From the ER to the inevitable rehab she can be transitioned to a permanent facility but have tempered expectations that she won't care about the socialization. I'm sorry for this distressing situation. It's hard on everyone in the family.

I'd make a video of you asking her one more time to go to respite care and her refusal. Then tell her (also on video) that you're having your son check on her, you'll call her every morning, and so forth. That way you have solid proof that she is making the decision to fight you.

Then go on vacation.

If her doctor doesn't say she is incompetent, then you have to let her make her own bad decisions for herself.

To add on to CM's theme..

Family is family, yes, but made up of individuals. Who can make decisions *for themselves* not for others.

A Social Worker told me this:
1. Give advice
2. The person makes a decision - 'good' or 'bad'
3. The consequences are theirs

But I get why you just don't sail off & wish her luck.. you feel a great obligation. Fear (to leave her), Obligation (only family) & Guilt (forcing the respite care). This is F.O.G. (Google this term of you like, it blew my mind when I did!)

So MIL is dependant on you & your DH but refuses to be looked after by others when you are away? I am wondering about her problem solving & planning ability 🤔

Does she understand but taking a stubborn stance as a gamble she will win & you will not go? (ie manipulation)

Or does she NOT understand her care needs (ie lack of insight?)

MIL's Doctor's opinion on this aspect could be a good idea.

For people being stubborn as a rock.. not going etc, using a firm stance back that you WILL be going may work. Try explaining they will be home ALL ALONE. Not to be cruel, but to break through.

For those lacking insight, tricks may be required.

The last resort may be go but build as much safety around as you can. This may inc;
- ensure she has a phone
- her Doctor's number preset
- ask neighbours to check-in
- wellness check from local Police/Fire
- easy open snacks/drinks

Call the Doctor to advise MIL is a vulnerable elder home alone.

Then tell MIL to call her Doctor for any problem & go.

You may only need to inform MIL of this plan with assertiveness for her to back down. Best of luck & Bon Voyage 😄

We have one of those too. My BIL/SIL are live in caregivers and we are the only backup option. My nephew (their son) was getting married at a destination 6-8 hours away depending on traffic. FIL was invited but logistically it was just impossible.(he's mostly homebound and travel is a nightmare, plus they were getting married on the beach and he wouldn't have been able to attend that anyway with a mobility scooter and the only beach access over the dunes)

So, we decided to book respite care. Thankfully we had some help from the VA. But it wasn't fully covered, so he was hot under the collar about having to pay for his own care (the horror). He decided that he could take care of himself. Spoiler alert - he cannot.

We got his reluctant permission to book home care and went ahead and booked it, working with the provider and the VA and scheduled everything - with him insisting that he didn't need it. We were going to be gone for a week. He kept saying he didn't need them and that once we were gone he was just going to send them home anyway because he didn't have the money to pay for them (he did) and that if he needed help we could just come home.

Some little voice in my head told me to cover all of the bases so I called APS. Not to report anything but just to get advice. I just said that I had a question and explained that we had a vulnerable senior who was competent but physically incapable of taking care of himself. That we were traveling and has scheduled 24/7 care for him for the duration of the trip and he was strongly suggesting that once we were at our destination he intended to fire them. The person chuckled and said they heard that a lot. They said that all we could do from our end was strongly remind him that if he did do that, he'd better be prepared to sit alone for a week with no prepared food or REALLY be able to take care of himself, because we have done everything we can to make sure he is taken care of for the time we are gone and HE would be the one that is removing that help. BUT no, we would not be legally responsible for that - we left him with care - he removed the care.

So we spent a lot of time really reminding him that if he fired them we wouldn't be coming home (I think he thought at the last minute one of us would stay home). We left for our trip and stayed up to date with the caregivers. Ironically - HE didn't call one time - which is unusual. We had to call him to check in. He didn't fire them. He actually enjoyed having someone new to tell his stories to. He was kind of sad to see them go. We started off with three shifts of three but they whittled it down to two shifts of two before it was over with. He sleeps a lot so they had plenty of down time. And it was the same two for most of the week.

I never in a million years would have thought it would go so smoothly with him. He is a dyed in the wool narcissist so I was 100% waiting for the call that he fired them and that he was expecting us to make the 6-8 hour drive home.

"Legally we cannot force her to do this unless we have guardianship and we do not." As someone else said, the next time she falls and can't get up, hae the ambulance take her to the ER to check her over. Then tell the hospital she is no longer safe at home because you are unable to care for her. A social worker will get involved. She cannot be left alone.