to commission, to entrust to, to depute, to request, to ask
侂 centers on transferring responsibility to another person: commissioning, entrusting, deputing, or requesting someone to act on one's behalf.
侂 combines 亻 (person) with 㡯, which likely contributes the sound and may relate to entrusting or placing something with someone. The exact historical development is uncertain.
A person 亻 beside 㡯, a shape that suggests placing something in someone's care. Picture handing over a task to a trusted deputy.
For タク, imagine entrusting a task to someone and saying 'tack it onto your list': tack -> タク, as you depute the work.