The expression を兼ねて is used to indicate that an action serves two or more purposes simultaneously. It attaches to a noun representing one of the purposes, conveying the idea of "also serving as," "doubling as," or "also for the purpose of." The action described in the main clause fulfills the stated purpose in addition to its primary or obvious purpose.
The basic pattern is: Noun + を兼ねて + main action
The noun before をかねて兼ねて represents the secondary or additional purpose – the "bonus" reason for doing something. The main clause describes the primary action being taken.
You can also list multiple secondary purposes using も or connect them with と:
を兼ねた + Noun: The attributive form, used to modify a noun. It describes something that serves a dual purpose.
を兼ねている: Describes a state where something doubles as or also functions as something else.