How many years does a person missing can be considered as deceased in China?

Question

My grandpa had 6 kids, but only two of them survived, the other 4 were either dead or missing, my aunt was missing since 1971 and she was never found, my grandpa still mumbled her name before he died. My family gave up searching her after 7 years.

Now we want to buy a grave and “fend" for her along with other dead members.

Answer 1

7 years sounds good to me