If he marries his new partner unless he has made a will leaving the properties to his daughters, on his death the usual rules of intestacy will apply. These only apply to married couples. If they are not married (or in a civil partnership, which will not apply here), the partner has no entitlement to any part of the estate. but can go to court asking for support if they can prove that they were dependent on their partner for any reason, for example they worked in the partner's business without pay or had a disability.
The rules are as follows:
If there are surviving children, grandchildren or great grandchildren of the person who died and the estate is valued at more than £250,000, the partner will inherit:
•all the personal property and belongings of the person who has died, and
•the first £250,000 of the estate, and
•a life interest in half of the remaining estate. This means that they cannot sell or dispose of this part of the estate, but can benefit from any income, for example, if the money is invested. on the widow/widower's death the money goes to the children.