Fact is, until you either pass away and your Will or Revocable Trust is administered, or you give someone a completed gift during your lifetime, your heirs have no vested rights. None. What they have is an “Expectancy,” and they have no legal or moral claim on you or your property.
In the case of Irrevocable Trusts, the Beneficiaries of such a Trust may have some vested rights, but Irrevocable Trusts are more esoteric and complex estate planning vehicles that most people don’t need and shouldn’t consider.
So this is a short answer to a short question. Your heirs have exactly zero rights to your property until you either give it to them outright, or you pass away and they get it by inheritance.
(By the way, the technical, legal term for those who will receive property through your Will is “Devisee,” and “Heir” refers to those that the law would direct your property to if you die without a valid Will. But the popular terms are “Heir” and “Inheritance,” so we will stick with the familiar to you who aren’t lawyers.)