Hi
Presumption I:
1) It is presumed that the man got married again after the demise of his first wife.
2) So if the above presumption is true, then the legal heirs of the deceased man in accordance to Section 8 of Hindu Succession Act are
a) Second wife, Daughter from First wife, 2 Sons and 2 Daughter's from second wife.
So technically the property of the deceased man will be divided equally in to 6 parts.
Presumption II
1) if the man had married the second time when the first wife was alive, then the second marriage is illegal.
2) However the children from both the first marriage and second marriage are entitled to equal share of the properties and the properties on the children will devolve in accordance to Section 8 of Hindu Marriage Act.
3) All of the children (Daughter from First wife, 2 Sons and 2 Daughter's from second wife) will have 1/5th share in the property of the deceased.
4) Second wife will be excluded from succeeding to the properties of the deceased man as her marriage is illegal and void on the grounds that her marriage happened when the first wife was alive.
Hope this information is useful.