Wouldn't it though be like how SpongeBob brought back it's one-off characters and made them recurring in the very later Seasons?

DARN IT! I need to stop falling for these hacked scams! I'm sorry this has happened to you. ☹️

However, would you want the new additional kids in HGF! to have their own character arcs where they learn how to fit in with the kids of Harvey Street with them taking the spotlight from the Harvey Girls at times making them look like the new main characters?

Though, we would not want this to be a Fairly Odd Parents situation with how that show handled it's additional new characters in it's final two Seasons.