A Joint Will is a Will made by two or more testators in a single document, duly executed by each testator, disposing either their separate properties or their joint properties.

Wherein in a Mutual and Joint Will, the survivor should have received the benefit under the will and there should be an agreement as not to revoke will.

In joint will survivor enjoys the properties absolutely wherein in joint mutual will survivor do not get to change the terms of the will which may be required due to circumstances.

So it's always better to have separate will rather than having joint Will especially Joint and mutual will.