Grandma died, does the grandson have to kowtow when he enters the door

I don't know if you're talking about a traditional funeral or what kind of funeral. If it's a traditional funeral, you're not the one crying, it's your father and his siblings. You only need to kneel in front of the spirit for three hours a day and burn paper money to show filial piety.

Greeting guests, buying wreaths is not the turn of grandchildren, otherwise it is a robbery of parents, and there is a suspicion of committing a crime. Because none of the grandchildren were the organizers or directly responsible for this funeral. However, in modern times, grandchildren are generally very large, for example, if they are adults, these things can also be shared a little, and in addition, wreaths or something are not collateral relatives, if they are immediate relatives, there is no need.

For example, in some places, there is a tradition of carrying corpses, which must be done by sons, such as supporting coffins, which must also be direct people such as sons, including grandchildren. But the one who carries the banner must be a son, and the one who carries the photo must be a grandchild (direct lineage), and it is generally close to the old man before his death. At the time of burial, kowtow is sufficient.

But I haven't seen anyone who didn't cry at that time.

We do not kowtow when we enter the door, and only when someone else comes to the wake, will we buckle our heads.

Yes; It mainly depends on local customs;