Unanimity is the whole requirement
The single most important rule in this process is that it takes everyone. A division agreement that one eligible heir never saw or never signed off on can be challenged and unwound later, sometimes years after money or property has already changed hands.
This is general information, not legal advice
What must be included in the agreement, how signatures need to be verified, and how courts handle a minor heir's conflict of interest all vary by country. Consult a local probate or estate attorney, especially when a minor heir or a disagreement among heirs is involved.
Frequently Asked Questions
Can heirs divide the estate differently from a will's stated shares?
In many jurisdictions, yes β if every named heir agrees, they can generally redistribute shares differently than a will or default statutory formula specifies, since the agreement of everyone entitled overrides a default arrangement.
What if one heir refuses to sign?
Without that heir's participation, the agreement generally isn't valid. The usual next step is for the other heirs, or that heir, to petition a probate or family court to resolve the division instead.