Dynasty Trusts

Dear Len & Rosie,

We have three grown children with children of their own and we have a trust. We want our children to be the beneficiaries but want to set it up so that, should they divorce, the spouse would not have a right to the inheritance. I know that an inheritance comes into the marriage as separate property but I thought that, if the pool is used for community expenses, mortgage, etc. that the whole thing could become community property. Yuk. Is there a way to ensure that it will stay separate property? We don't mind if our children purposely use the funds for their families, but would like to set it up so that they can keep the remainder of the inheritance should they divorce. What should we be looking for?