Here's a bit from personal experience (I get to post it at least once on every forum
At a Japanese funeral service/cremation, the hashi
have a special purpose and this is why you don't see people passing food from one set of hashi
The Deceased is placed in an all-wooden coffin which is passed into the oven for cremation. The family then repair to an ante-room where they partake of drinks and snacks for... half an hour or so. Then everyone returns to tke part in a highly symbolic moment. The remains in a Japanese cremation are not reduced to the white powdery ash that you see in a Western urn. The family gather around a table where the ash and bone fragments are to be picked up and placed into a small wooden box (about 1 cubic foot). The people form pairs who pick up a fragment between them and place it in the box. Some bones survive cremation better than others, the largest vertebrae is particularly important apparently, there are enough for even a large congregation. All the bones are collected and the ash as well (IIRC). This box is then carried by one of the closest family members for the subsequent rituals.
This is the only time two people are allowed to pick something up with hashi
I've seen this in Japan. I don't know if it is a tradition from China or not.