Would this transaction be included in Belinda's estate?

Trust created under the will of Belinda's mother (who died in 2000). Belinda herself is also now deceased and Belinda was entitled to all the trust income for life, and she was given the right to assign the trust remainder to whomever she desired via her will. She willed it to her sons in equal amounts.

Since she was able to name by will whoever she wanted to, isn't this trust included in Belinda's estate? Please confirm why/ why not.