My partner and I share everything we eat. I think we have passed food between chopsticks before. What's the "proper" way to do this? Just reach in to the other

My partner and I share everything we eat. I think we have passed food between chopsticks before. What's the "proper" way to do this? Just reach in to the other bowl? Also wondering how many of these apply in a Chinese setting or any other chopstick culture. Are there a different set of taboos?