3 things. We don't do cremation in my family, so far, though my sister might, IDGAF The best burial in my opinion is in the dirt, with no vault, have a coffin or a shroud but in the dirt but no massive concrete forever box unless it's a proper tomb, frankly I'd like a wooden coffin like they had in the old west. A friend of mine is starting a copycat company, where you ship him your ashes of the deceased, a person or a pet, and they use a kiln and heat and compress the ashes with a bit of infill material and turn them into stones, I'm looking for a cheap laser engraver they can use to inscribe onto the stones without a deft hand or artisan, the idea I gave him after I heard about this was that cairns are unmistakable to our cultural identity, if you see a neat pile of stones stacked in just the right way you know it's a burial or memorial site for the dead, I'm sure other cultures have done it but if you are in euroepe you know that is the only thing it should mean, it's a core ancestral thing to us I believe, it resonates with us so if you are going to keep a relative's ashes keeping them as a cairn at your mantle place, hearth or in your back garden perhaps seems logical, if your grandparents die and you have both ashes I've heard of some people mixing them into a larger urn but if they are stones you could just make a larger cairn; ironically his family own a vault company.