The answer may well lay in whether HMRC still accepts the court’s decision in Evans v. Lloyds Private Bank. I cannot locate reference to the case (I hope it is referred to in Dymonds), but recall the court held that no IIP arose where property was given to, say, the children with a request that they allow the widow to reside in the property.
If Evans is still good law, the devise can be drafted along the same lines - as an absolute gift to the children I would expect it to qualify for RNRB.
Long term, though, would the immediate IHT benefits be negated by any potential CGT liability and, possibly even, the 3% SDLT charge on any future purchase of property by the children, whether for their own home or otherwise?
Paul Saunders