He notes that even if one's parents or in-laws were extremely pious people and everyone left behind is confident they're doing great in the Afterlife, one can never really know for sure.
Therefore, it's best to go beyond the yearly kaddish and other traditions of honoring our dearly departed.
He notes that it's not enough to do all the important things one does during the 12 months following a parent's death.
No one can rest assured regarding one's fate after death, and so children and children-in-law should continue to pray and perform good deeds (like giving charity) on behalf of their parents for the rest of their lives.
In fact, he even goes so far as to say:
It is proper for a son to have his father's image etched before him all the days of his life as if he appears screaming bitterly from amid flaming fire and saying, "My son! My beloved! Have compassion upon me! Have compassion upon me! Save my soul from the sword and my being from the grasp of a dog!"
Their departed souls will bless our living souls and God will also be very Happy about our concern and compassion for people who are no longer able to help themselves.
So providing merits for departed loved ones is an all-around win-win situation for everyone involved.
To this means, Rav Papo composed a short prayer to say, and he recommends that it be said at the beginning of each day.
Where it says "etc," you can apparently fill in whatever person you choose. You can also apparently say this for a grandparent or anyone else for whom you wish to provide merit in the Afterlife.
You should also feel free to change the Hebrew possessive in the last line to feminine form or plural, if necessary, i.e. instead of nafsho, you can say nafsha for a woman or nafsham for several people.
Here is the prayer in Hebrew, English transliteration, and English translation: