Can our daughter's partner benefit from our joint will?

We’re worried that after we die he may be entitled to half our propertyQ Our daughter is the sole beneficiary in our joint will. Our entire estate is left to her and her only. However, she has a partner who is the father of our grandchildren and who, shall we say, is and never would be our choice of partner for our daughter. Unfortunately we cannot change this, it’s her choice.What worries us for the future, after our passing, is that if he stays with her and marries her whether he w