This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 伖 is uncertain. It combines 亻 (person) with 友, but the original meaning and component function are unclear.
A person 亻 beside a friend 友 might suggest companionship, but the actual meaning is unclear.
For トウ, imagine a person and a friend towing a rope together: tow -> トウ, though the meaning remains uncertain.