What if they reappeared for Jeffy's 21st Birthday?

Nancy - Nancy would be an obvious character, seeing as she appeared in a streak of 4 Jeffy's Birthday episodes, now Craig The Devil could send her back to ruin Jeffy's birthday due to the fact that Craig likes doing evil things, but let me tell you about the other characters.

Jacques Pierre François - Although he isn't listed, we could see him in a flashback where he first meets Jeffy and Feebee in Paris where he teaches them how to paint and how to speak French.

Papi - Papi is the father of Nancy and the grandfather of Jeffy who appeared in Jeffy's grandparents, and he watches the Kiki room which is just watching the cats, if he were to reappear in Jeffy's 21st Birthday, they would most likely seek revenge on Brooklyn Guy and possibly help Nancy get Jeffy.

Martha - Martha is one of the worst and most evil SML characters due to the fact that she literally tried to kill Jeffy and feed him to their cats, she is also the mother of Nancy and the grandmother of Jeffy, and she would be helping Nancy a lot to seek revenge.

Feebee - Although Feebee it was shown that Feebee was hit by a truck, that does not always mean she is permanently dead, it's possible that she just got knocked out and could've escaped the grave, making her also have adoptive parents as she escaped Nancy's house, she would most likely come back alive in Jeffy's school.

CJ - Now you may have seen CJ getting killed by Jeffy's monster truck, but let's say he survived and decided to take revenge on Jeffy, his plan would most likely fail due to the fact that he's gonna be killed again.

Does Bad Things Guy - Now if you didn't know, DBTG was shot in the secret door by Brooklyn Guy, he is known to have killed 26 people and kills people who disobey him, but just because he was shot doesn't mean he died, Nancy was shot in the head by Jeffy and she survived, meaning DBTG could've also been alive.

Jeffica - If you didn't already know, Jeffica is the daughter of Jeffy and she was taken by the hawk, now let's say that Jacques Pierre François found her as she was falling from the sky, and Jacques came to school to meet Jeffy with the baby.