First, the sitting direction of the powder mountain.
Second, the date of birth of the deceased (mainly the date of birth, the month is for reference only, commonly known as "longevity").
Only by knowing these two points, can we avoid the collision between choosing a date and the tomb mound and the immortal life, and bring out the noble and lucky people sitting on the mountain and the immortal life (expressed by heavenly stems and earthly branches at the selected date), so that the dead can enjoy peace and the living can get wealth. But if you really don't know the year of birth of the deceased, you will be buried according to "good luck". And it is necessary to sit in the powder mountain, otherwise you don't have to choose a date!
However, burying ancestors is a serious matter and must not be hasty! For the safety of your family, Kenichi, you should find a well-known local Feng Shui master.