Variation from one deceased’s Estate to another

A died.
B was alive at the time of A’s death but did not benefit under the terms of A’s Will at the date of B’s death.
B has since died.
Is it possible to vary A’s Estate to B’s Estate, on the basis that B survived A?

In essence, I am asking, is it possible to vary from one deceased’s Estate to another?
For background, if this is possible, it will be advantageous from an IHT point of view.

It is possible for A’s estate to be redirected in favour of B’s estate. There is no requirement for a DoV to effect a redirection of A’s estate to a beneficiary of A’s estate.

Malcolm Finney