I copied the criteria for obtaining a plenary indulgence for the Poor Souls from this site:
On all the days from November I though November 8 inclusive, a plenary indulgence, applicable only to the Poor Souls, is granted to those who visit a cemetery and pray even if only mentally for the departed.
Conditions for both indulgences:
1. Only one plenary indulgence can be granted per day.
2. It is necessary to be in the state of grace, at least by completion of the work.
3. Freedom from attachment to sin, even venial sin, is necessary; otherwise the indulgence is only partial. (By this is meant attachment to a particular sin, not sin in general.)
4. Holy Communion must be received each time the indulgence is sought.
5. Prayers must he recited for the intentions of the Holy Father on each day the indulgence is sought. (No particular prayers are prescribed. One Our Father and one Hail Mary suffice, or other suitable prayers.
6. A sacramental concession must he made within a week of completion of the prescribed work. (One confession made during the week, made with the intention of gaining all the indulgences, suffices.)
Here is Theodore's grave. We shall be getting a headstone for him soon. Unfortunately we can't have an upright monument, because I would prefer a Celtic cross for him. I took this picture from the head, and Marc is by his feet.