AOD,
If they are Ties from around here, it ain't just creosote on 'em.
They are Toxic. The Fly ash is a real hazzard for them. It could kill them.
The RR guys down here will tell ya flat out that slivers from those things are worse than treated lumber, especially the older ones that were laid down and are just getting pulled up now. Back in the day, the Ties around here were treated with LOTS of evil crap, plus the Creosote because of the wet rot problems.
I understand the old Dutch farmer issue, good luck with that.
Maybe someone could dig up the news article about the family that got sick and dead from burning treated lumber, and you could kinda break it to him.
I don't think he would knowingly endanger his grandkids.
All ya can do is try I reckon.
Stay safe!
Dingeryote