It is difficult to respond without reviewing the trust. If the "premarital" agreement recites (as they usually do) that the consideration is the ensuing marriage it may be that the premarital is no good; but, if the trust incorporates the premarital by reference the trust may prevail. You must consult a competent probate attorney to determine your rights.
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My advise to you, if it makes a difference in the amounts you will received because of your husband's death, is to seek out the immediate advice from a probate lawyer in your area. Only an attorney who has reviewed the agreement and declaration of trust can advise you.
If each agreement was executed with the required formalities each agreement will be “valid.” However, the devil is always in the details. The ambiguity you mention, or others, could result in a distribution under the trust different from what you believe was intended. So, it’s important you have a probate attorney review the documents and advise you. Good luck.
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The "premarital" agreement wasn't really a premarital agreement, it was a POST-marital agreement, and the rules for enforcement are different. You need to speak to an EXPERIENCED EXPERT trusts/estates attorney to straighten this out.