Pearlsasinger
Up in the clouds
If I understand this right, this horse was sold under Norwegian law and if this woman wishes to pursue her case she will do so under Norwegian law? If that's the case I don't think an English vet or an English forum necessarily know anything about how it might play out.
It does seem that the woman has no leg to stand on BUT I have no clue about Norwegian laws. I would strongly suggest you spend the money required to contact a specialist, Norwegian, equine solicitor to advise you on the first step, rather than do something yourself than might affect a potential defence later. It is really stressful and unfair that you have to deal with this, but I think you have to deal with it, in which case it is better to get professional advice and do it right.
I hope the woman gives up after your solicitor's letter.
I completely agree with this. Unless there happens to be a forum member who is a Norwegian solicitor, with knowledge of the law as it pertains to buying/selling equines, you are only going to get guesswork answers. My advice would be to keep all contact to telling the buyer to contact your solicitor and to get yourself one asap.
(I have to say that I sometimes read comments on English law on here, which I KNOW to be nonsense, so goodness knows what sort of rubbish you could get about Norwegian law).