The short answer to this question is yes. But here is the reason why.
Marriage revokes a will. Therefore, any will made before your father married will be cancelled (but see below for the exception to this rule). If he does not make a new will then the intestacy rules will apply. These rules set out how an estate should be distributed if someone dies without a will. If your father dies without a will and he is married and has children then the distribution works like this. The surviving wife will receive the first £250,000 from the estate and all of the personal possessions. The remaining sum is split so that half will pass to the surviving wife and half to the children of the deceased.
However, your father might own some assets jointly with his wife and they may pass automatically to his surviving wife. Where assets are owned jointly they may be owned as what is called “joint tenants” or “tenants in common”. Basically, if a couple own an asset together as joint tenants then that property will pass automatically to the surviving owner. If the deceased had no will then the intestacy rules would then only apply to the remaining estate.
Just to give an example, imagine that husband and wife own the family home jointly as joint tenants. The house is worth £500,000 and the husband has savings in his sole name worth £250,000. The husband dies. The house passes by survivorship to the surviving wife. The rest of the estate is worth £250,000 and the intestacy rules apply to this. Therefore, all of the estate passes to the surviving wife. This might be exactly what the family want but very often, where this is a second marriage, this is not what families want. The couple will often want to ensure that their estate passes to their children.
It is possible to anticipate these issues and make a will before you re marry. The important thing here is that the will must say that you are making the will in contemplation of your marriage and that the will should not be revoked by that marriage. This is the only way to prevent the marriage cancelling your will. If your father has a will from before his marriage then he should just check to see if it was made in contemplation of marriage.
Your father has already married and it is therefore vital that he takes advice not only about a new will but also about the way that he owns his property.
There are various ways that a will can be constructed to ensure that the couple provide for each other but also ensure that their own children inherit their estate in the fullness of time. We frequently advise couples who are marrying for a second time and can advise on a fair and sensible structure for their wills.