Years ago I once picked up my unaccompanied 11 year old Godson flying in to the UK. It was a big deal. His mum had to fill in a form and confirm who was meeting him and I had to take ID etc to claim him. It took a lot longer than just meeting an adult passenger, because I had to wait until everyone else was let off the plane, and then all the unaccompanied children gathered, and all IDs checked, etc before he was finally handed over to me.
Once he was handed over, I became legally responsible for him until he was delivered to the next legally responsible authority/ adult.
This is quite a lot to ask of you, a big responsibility, and only something most people would ask of a very close friend (like the kid’s Godparent).
Nevertheless, I think you would be seriously unreasonable not to reply, when all you need to say is “No.”. Two letters. Not for your “friend’s” sake, but for the child. If she is a CF enough to ask you to do this, she may be a CF enough to assume no reply means yes.
By all means type the word “No” , send, and then block her. But don’t leave any possibility for misunderstanding. Yes, if you do, she will be punished: the airline will have no one to hand over the child, and once it becomes obvious that the person named on the form isn’t coming, they will call SS - who then will take over legal responsibility. A big mess will follow, with the child likely to spend a night or two in foster care - and the mother, of course, will be wholly responsible for the mess.
But the child will no doubt be really, really distressed by the mess. You might be able to save that distress just by a simple one word, two letter text.
No, you don’t owe it to her, but I’d send the text anyway.
I have read most, but not all, of the thread, so apologies if I have got this wrong. I was under the impression that you were proposing to say nothing - no reply - and letting her assume whatever she wants to assume - including that your silence means it is all sorted.
Also, in case she isn’t totally irresponsible, if you don’t reply, you will probably get a lot more texts in the next couple of days, increasingly urgent, begging, and then nasty, and you might want to avoid that.
TLDR: text “NO” and block.