Can my husbandhave aTrust/Willwhichprovides that everything goes to his daughters fromhis first marriage?

Of course you have rights.  You are a very wise woman to think ahead.  But this is not one of those matters that you should be afraid of talking with with your spouse.  It is one that you need to discuss head on to insure that you are well taken care of when and if he passes away first.  So as you aware, there are laws that prohibit a spouse from being disinherited from the other spouse's Will should the other spouse die first.  The elective share laws vary from state to state.  I Florida it is 30% or the "elective estate" which is computed in not a very easy manner.  It is possible that if you are left 30% of your spouse's elective estate but are not happy about what you were left that you could be precluded from bringing an action because you technically were left what you would have gotten under the laws and its computations.  Speak with your husband and an attorney or estate planner.  Good luck. 

It is my understanding that Florida is a community property state. If so, your husband most likely can leave to his daughters from his first marriage through a Will or Trust one-half (1/2) of of his interest in the community property that you and he have from your marriage and all of his personal separate property that he alone owns.

However, if you have a written agreement with your current husband signed by him stating that he is to leave you some of his separate property and/or his one-half (1/2) interest in the community proeprty that you and he have, then the written agreement would control over any Will or Trust.

To confirm the above, you should consult with a Florida estate planning attorney.

Good luck.