Doesn't a "tontine" (yes, correct spelling) mean that the property passes to the surviving partner (the wife, normally, natch) rather than passing directly to your children.
Which potentially could result in a disinheritance, if your children are not hers.
(Isn't this a workaround to avoid inheritance tax on the property passing immediately to the children on the death of the first parent?)
Almost ... the property passes on to the kids but the surviving spouse gets to stay in it until (s)he dies or decides to sell. The kids cannot legally force her/him out.
Equally, the kids have to agree to her/him selling .... but why would they not?
In the words of the song ... no-one said it would be easy.