Have you considered how confusing it is to kids when adults “pretend to be the priest”?
It might be much better to ask your priest to come lead that part and have you adults be the ones playing the part of the penitent child instead of the actual children.
I’ve also known of kids who got very confused because their teacher told them. "When you go to confession, Fr. John takes your sins . . . " Then they saw Fr. John talking with their mothers afterwards and wondered if Fr. .John gave their sins back to their moms and told them everything. Oh these kids were terrified of that possibility!
Hope this helps . . . .
Penitent: Start by making the sign of the cross and saying, “Bless me father for I have sinned…” Then state how long it’s been since your last confession: “It has been (so long) since my last confession.” Or, tell him it is your first confession.
Priest: Will offer some kind of welcome. Could be “Hello Timmy!” or could be, “May God the Father of all mercies help you make a good Confession.” (It really depends on the priest!)
Penitent: Begin to confess the sins. Be specific so the priest can offer help. Also, give him the number of times like, “I hit my brother three time this month. I disobeyed my mom once or twice.” When finished, say, “I am sorry for these and all of my sins.”
Priest: With this information, the priest may counsel us. He also assigns a penance for the healing of the hurt caused by sin and the strengthening of our soul against future temptation. He then asks us to say an act of contrition,
Penitent:: “Oh my God, I am heartily sorry for having offended Thee. I detest all of my sins because of Thy just punishments, but most of all because they offend Thee, my God, who are all good and deserving of all of my love. I firmly resolve with the help of Thy grace to sin no more and to avoid the near occasions of sin. Amen.”
Finally, the priest imparts absolution. “God the Father of mercies, through the death and resurrection of His son, has reconciled the world to Himself and sent the Holy Spirit among us for the forgiveness of sins; through the ministry of the Church may God give you pardon and peace, and I absolve you from your sins, in the name of the Father, and of the Son, and of the Holy Spirit.”
The priest then dismisses us, saying, “Give thanks to the Lord, for He is good,” to which we respond, “His mercy endures forever.” (Many priests may simply say, “May God bless you.”)
Then leave the confessional to do the assigned penance.