The person who will pass on their wealth may wish to consider your daughter could agree, or be quietly compelled, to waive protections under a pre-nuptial agreement.
However, if the assets are put into trust for her benefit, the trustee can protect squandering or deceitful grasps of assets while providing for your adult offspring.
It is very easy to prove that inherited assets are co-mingled and therefore joint property. It is also very difficult to ensure that all inherited assets remain separate and apart, especially if the marriage is long lasting and/or they have children.
The safest way to protect any potentially inherited assets from your daughter's future husband would be to put them into a revocable trust that spells out how the inherited assets should be handled.
I encourage you and/or the family member who may bequeath the assets to your daughter to visit with an attorney familiar with trust and estate planning and determine if a trust would be the most appropriate way to protect any inherited assets from your daughter's future spouse if that is truly a concern.