To be so upset people think we left without paying?

Spam the post with your own family’s comments.

X post with you.
Keep posting and tell them you are being harrassed because of them and will be looking at your legal options.

To be clear - is it the couple in the foreground who are alleged to have failed to pay?

If so, I'd be all over that photo on social media!

"Hi manager, to be clear we have tried to speak with you on the phone and sent messages but you refuse to remove the photos of our family celebrating with you today. As you already know, we paid in person and in full at the time for our bill of (amount) including a generous tip for the service.

You have now put up this photo and have refused to clarify that we are NOT the ones who have run off without paying, and you are now allowing people to make claims that we are thieves which you know is not true.

If you do not remove these images and provide a sincere apology, we will be forced to take legal action to protect our good name.

We also have a booking with you for x people on Thursday. Please consider this notice that the booking is now cancelled and we will not be returning to your restaurant given how we are being treated.

We have lots of sympathy for you at the loss of money in the current climate, but to use images of my family and children to spread lies or to try to go viral on social media is absolutely unacceptable"

Or something along those lines!

So you've tried being reasonable and they still don't want to know.
Leave them a 1* review on Google/Trip Advisor or the like and get the 14 people there with you to do the same. This will grab their attention and might just get them to remove the picture.
And if they do contact you, tell them that their actions have lost them 20 paying customers for next week and on all the other weeks you'd be going and spending a lot of money.
I ran a business for years. I get how hard it is and I know how much pressure there is to make ends meet but this just isn't the way.

Sue them.

Threaten them with this

So basically it was the couple who hadn't paid, but your party is clearly in the picture posted and the owner has put somewhere in the text, "the people in the birthday party were not involved"

However, people can't be bothered to read and have jumped to their own conclusions that it was you who hadn't paid.

I think the owner needs to make it very clear that it was not you.

He should do a close up of the couple involved and blur you out

https://www.dailymail.co.uk/news/article-14678733/family-accused-leaving-restaurant-without-paying-win-damages.html

I would be absolutely furious about this! They've lost a good customer and rightly so

Report them to who?

Do you have proof that you paid?

I saw a comment on another post recently that said its a breach of GDPR to share images of CCTV where people in the background are identifiable. I'm not a lawyer so I don't know how true this actually is, but it might be worth messaging the restaurant again saying they've breached GDPR and if they don't remove the image immediately I'd be seeking legal action. I'd also trash their ratings by leaving reviews on Google and TripAdvisor detailing how you've been treated, maybe that will get them to take it down.

I'd make the restaurant aware that A family have just successfully sued over a similar incident where they were accused of not paying and slandered online.

https://www.google.com/amp/s/www.bbc.co.uk/news/articles/cvgny7epgvpo.amp

Have they said why they won't take it down if you've proof you have paid or is it a case of someone pocketing the money and you have no proof?

ETA - sorry I misread is it the couple who have not paid in which case I suspect you could still have a case as it looks like it's referring to your family?

Can you post a photo of your receipt, not that you should have to!

Send them a message saying you are going to report them for using your child’s image without your consent