Question

Beneficiary is one who unintentionally gains a benefit from a contract between other parties

Answer 1

The answer is "incidental beneficiary".

An incidental beneficiary refers to somebody who indirectly acquires an advantage as the aftereffect of the fundamental reason for the trust. An incidental beneficiary is a recipient who isn't a planned recipient. For instance, a grandchild may profit by his/her parent accepting a blessing which could be utilized by the whole family, or which he/she may acquire from the parent.