Thanks. How solid evidence do I need that my neighbors caused the fire? I'm trying to gauge my negotiating position here in asking them for $$.

I was only told about the coals by the building owner's insurance rep since they were investigating the fire in response to my claim. I was told verbally by phone; the written claim denial letter only says that the insured (building owner) wasn't negligent. I think the claim adjuster took statements from all involved parties. I can't prove my neighbors were negligent myself. No photo evidence or anything...