My mother’s new grave which is less than a year old has partially sunk due to rain. Can you please add some soil?

There are generally two reasons for this situation. One is that the filling with soil after burying the maternity hall was not solid. Many places were hollow and sank due to rain. In addition, the water in the cemetery was not treated well, and the rainwater accumulated around the tomb. It was soaked for a long time and then sank. You can see which is the case. If it's the former type, just fill it with some soil, it doesn't count as disturbing the grave. If it is the second type, the effluent needs to be treated so that the rainwater can flow away and not accumulate around the tomb.