In purgatory, the souls of many of those who have died in God’s grace undergo purification so that they may enter heaven. We cannot know for certain if our loved ones have transitioned to Heaven. Even if they have, other souls in purgatory need our prayers.
St. Gertrude, a Benedictine nun and mystic, wrote prayers for souls in purgatory. She lived in the 13th century and received assurance from our Lord that the following prayer would see 1000 souls released from purgatory each time we pray it with devotion.
You can wish to add this to your daily prayer life.
Eternal Father, I offer Thee the Most Precious Blood of Thy Divine Son, Jesus, in union with the masses said throughout the world today, for all the holy souls in purgatory, for sinners everywhere, for sinners in the universal church, those in my own home and within my family. Amen.