Allways the optimist.
Hmm, yeah, but I think in this litiginous(sp?) society, it needs serious consideration unfortunately. Agree with lilbit about written agreements & I'd be inclined to try to help the horse & keep written records of everything including reasons for doing what you're doing.
Agree basically with everything said, except that I think hoopla is assuming & judging unfairly. Perhaps you know the people personally hoopla, but if not, who are you to say you 'don't buy it' based just on OP's post?? Many people have the best of intentions but lack the knowledge(or are advised badly) to provide appropriate care. If you don't know what you don't know & have no one to advise you otherwise, I don't think getting blamed for your ignorance is fair or reasonable. Based on what furbaby has told, I think they & their neighbours are probably doing the best with the knowledge they have and should be supported in that, especially that they're asking for help & advice(even if it's here, when I think you'd be better forgetting the forums in favour of a good equine vet & rehabilitation specialist)
IMO the horse needs a vet(& rads), farrier, strict diet(without starving it), free movement & exercise, & hoof protection in the form of padded boots or such, if it's not comfortable in it's environment. IMO your neighbours - & you if you want to take the horse on - need to do some serious research. I'd advise first-hand expert help, but to get you started, safergrass.org & hoofrehab.com will give you some good info to go on with. If you can't/don't want to put in the necessary effort, well, you know what they say about the road to hell & good intentions.... in that case, I'd agree with Mark & not touch it. I'd also be concerned for the other horses in your neighbour's care.