cloth to carry an infant on the back, to tie, to bind
綳 centers on binding or tying with cloth, especially for carrying an infant on the back. The core idea is securing something with fabric.
綳 combines 糸 (thread, cloth) with 朋, which likely contributes the sound. The character is used for binding or tying with cloth, consistent with the thread component.
The left side 糸 is thread or cloth, and the right side 朋 looks like two bound bundles. Picture tying cloth around a baby to carry it on your back.
For ホウ, imagine a cloth binding a bundle while you say 'hold' with a Japanese accent: 'hō' -> ホウ. The cloth holds the baby securely.