Gave parents gift, they used to payoff part of mortgage...

[Edward L.]

Hi all, I gave my parents a large gift that they used to make a principal payment on their mortgage. They are enjoying the reduced payment amounts but said they want me to be entitled to the amount I gave them (instead of dividing it with my siblings) if anything were to happen to them.  The remaining equity would be distributed evenly among the family. Is a will the only way to accomplish this? Or should there be a lien on the property in my name?