If the person was cremated and the ashes scattered, then there is really no "grave" Sometimes a family will put a memorial marker with name and date on a family monument so there is record of the deceased person with other family members. That is what is called a cenotaph and is acceptable if it can be GPS imaged via the app. There are many examples in BG of persons who were killed in wars or lost as sea or other situations were the remains were not brought back to the family.
If the ashes have not been returned to nature, but are in an urn in a private residence or storage area, then there is not "grave". I know that other site allows for cremains memorials, but that is not what BG wants. BG wants a GPS image taken with the app of the final disposition site.
If the ashes are still held in an urn at a private residence or storage area, what to do? A possible work-around would be to find the BG record/photo of the nearest deceased relative (parents or grandparents) and make a note in the NOTES section that the relative is deceased with name and dates, and where the remains were known to be at that time. That way if a person comes looking for that individual in future, there will be a clue to the remains and certainty for the life and death.
If you know with certainly where the ashes were scattered then there is a way to create a record for that person.
I not long ago saw this case in the BG files:
1. A well known contributer who is on the east coast of USA posted a "grave" that was in the Atlantic Ocean shoreline, marking the exact place where the ashes were released to nature. He/she created a lone-grave cemetery at that location, and placed a photograph of a placard with the name and dates for that person. It was done very respectfully, and fulfilled the purpose of BG, which is to record the grave sites for as many as we can find.
Thank you for asking this question, as I have been wondering how to create a record for my own father. He did not want a burial in the place with the rest of his ancesters, but was cremated and his ashes scattered. Most are in the river in Florida were he lived all his life, a few were placed in Niagara Falls, NY and a few were tossed into the tidal bore of the Bay of Fundy Nova Scotia. I still have a small canister and hope to create a centotaph for him sometime in the future.