I had to particpate in this as well when my wife's grandmother passed away.
The tricky part is how two people have to pice up a bone fragment together and place it in the jar with long chipsticks. I've liver here long enough that they are no second nature on my own but I surely didn't want to be the one fumbling a piece of grandma when It came my turn. But it was fine, I teamed up with my middle son and it went smooth. The mother-in-law place grandmas glasses that she always wore on the top of the bones and then closed up the lid.
The family goes to the graveyard a couple times a year to wash the head stones with a scrub brush and I've gone a number of times to clean up the ancestors graves. And they alos have a little memorial shrine in the house that they will put out some food and right the bell to remember them as well.