habrán alegrado
Future perfect ellos/ellas/ustedes conjugation of alegrar.

alegrar

Estaban aquí y se habrán alegrado de lo que hemos vivido.
They were here, and they were probably happy about what we experienced.
Por lo menos tus padres se habrán alegrado de que los visitaras.
Well, at least your parents must have been glad you paid them a visit, huh?
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to pour