Okay so this whole thing is detailed and ridiculous, I'll cut the 'ideas' and leave the actual prompt out in the open.
McKinley School of Magic
~Will Schuester was the Muggle History teacher but gave the position to David Martinez who actually studied Muggle History (at a Muggle University). He is now the History of Magic teacher (which he actually loves and kids are finally interested in both classes)
~Emma is the school counselor and in charge of school cleanliness (which she isn't paid for, she just insists the janitorial staff have higher standards)
~Quinn Fabray transferred here after becoming pregnant. But later she is allowed to rejoin the Cheerios after negotiating with both schools
Quidditch Team- The Titans
~Lauren Zizses is on the Titans and occasionally sings with the Glee Club.
~Shannon Bieste arriving as coach gave the Titans their first successful season in almost a decade.
~She also started switching out her players multiple times per game. It confuses the other teams and gives the kids a breather.
~Karofsky and Azimo are Beaters.
Glee club- New Directions
~Rachel Berry and Finn Hudson are co-captains.
~Other members include: Kurt, Tina, Rory, Joe, Quinn, Sam.
~Members of both the Titans and New Directions: Mike, Puck, Artie, Lauren and Matt.
~~~~~~~~~~~Dalton Academy of Wizardry
~The school has a strict no bullying policy
~The teachers encourage the students to teach themselves but to ask for help with any subject if needed.
~Responsible older students are put in charge of younger ones and are responsible for their happiness and actions.
Quidditch Team- The Parulidae
~Sebastian Smythe is a popular Quidditch player and often flirts with Blaine Anderson.
~Coach Ken Tanaka is in charge of the Parulidaes practices but the team don't listen to his advice and they keep winning so he doesn't much care.
~Jeff and Nick are Beaters, with Thad as the Keeper. Trent thinks they're all crazy and David just wishes that Wes would stop combining Warbler practice with the Quidditch ones.
Glee Club- The Warblers
~Wes is pulling double duty, he's Captain of the Parulidaes and on the Warbler Council
~Blaine Anderson is the favored vocalist of the Warblers but he is considering tranfering to McKinley to be closer to his boyfriend.
~~~~~~~~~~~Crawford Academy of Witchcraft
~Carol Hudson is the school's Head Nurse
~April Rhodes teaches Divination in which she claims she gets visions from her special brand of tea.....which isn't tea at all.
~Roz Washington runs the Dueling Club but is after Sue Sylvester's coaching job.
Quidditch Team- The Cheerios
~After witnessing a Muggle "Football game", Sue Sylvester was inspired to create the first Cheer squad for Quidditch. (In reality she was the first person who made those who wanted to cheer at games become a group and practice intensely.)
~Becky Jackson is a Beater, as is Santanna. Brittany=Seeker, Quinn=Keeper.
~Sugar Motto bought her way onto the team with new brooms and Sue keeps her as a backup.
Glee Club- The Troubletones
~Shelby Corcoran transferred to Crawford after adopting Beth.
~Mercedes is the Captin of the Troubletones.
~Members: Sugar, Santana, Brittany and Others.
~~~~~~~~~~~Carmel School of Witchcraft and Wizardy
Quidditch Team-
~Sunshine Corazon is their Seeker.
~Jesse St. James was Keeper for one season before being pulled to focus on his amazing singing. (reality: he paid more attention to the crowd and hardly ever stopped the Quaffle from scoring)
Glee Club- Vocal Adrenaline
~Harmony is still young but is determined to crush all in her path to stardom. (Jesse practically adopts her and Sunshine outright avoids her)
~~~~~~~~~~~~Holly Holiday has substituted at all of these schools.
~Sandy Ryerson has worked at Dalton, Carmel and then McKinley. Each time his contracted has been canceled under interesting circumstances. He now works at Crawford and is under the scrutiny of Coach Sue Sylvester.
~~~~~~~~~~~The American Magical school system is better connected then others across the Globe. Various schools are connected by Floo Network. (and can be connected if a student or parent presents a valid argument)
They tend not to divide their schools up into houses but allow clubs/groups/teams to earn or lose points toward an end of year prize.
They also have buildings that are for students to meet up outside of school. (Floo travel to see a Broadway show with students from another school can be easily arraigned.)
American Witches and Wizards are more knowledgeable about Muggles and usually live amongst them. Wizard only towns are considered kind of silly to most but to others they are a status symbol (ex: Terri Schuester)
McKinley is run off national Wizarding taxes and is free to students. Both Dalton and Crawford are more expensive but if you show promise a scholarship can be offered. Carmel is invitation only.
McKinley starts at age 6. And at age 11 the children have a choice of continuing there or transferring to another school.
Rumors are that Carmel kidnaps children at birth and raises them in a secret location but this is unconfirmed. The other rumor is that parents gladly sacrifice their children to Carmel at the hint of an acceptance letter.
In addition, Dalton and Crawford are the only ones who enforce a uniform policy. McKinley and Carmel just insist on cloaks being worn all day and hats on special occasions.
Sue managed to get the Cheerios (the Quidditch team and the cheer squad for it) permission to wear their own special uniforms. Shelby countered and got permission for her Troubletones to accessorize.
Dalton allows options but no exceptions.
There are other American schools and many more in Canada, Mexico, Central America and South America.
Here's where the prompt comes in. During "Harry Potter and the Goblet of Fire", four American schools are invited to Hogwarts to play Quidditch to make up for canceling it for the schools in the competition. Those schools are Carmel School of Witchcraft and Wizardry, Crawford Academy of Witchcraft, Dalton Academy of Wizardry and McKinley School of Magic
The students at Hogwarts are confused by the lack of houses and why Quidditch isn't the only sport. (like Ultimate magical Frisbee and Bespelled Paintball)
The fact that these American kids seem to be friends while going to different schools is odd to them.
When they arrive at Hogwarts the different schools have to sort their students.
~Gryffindor: Sunshine, Mercedes, Jeff, Nick, Lauren, Rachel, Sam, Joe
~Sytherin: Kurt, Santanna, Jesse, Sebastian, Becky, Harmony, Jacob, Wes
~Hufflepuff: Blaine, Brittany, Karofsky, Trent, Sugar, Puck, Finn, Matt
~Ravenclaw: Tina, Mike, Artie, Thad, David, Quinn, Azimo, Rory
Or however you want it to go. Any characters I missed are fine to add.~~~~~~~~~~~Preferred Glee pairings: Kurt/Blaine, Santanna/Brittany, Puck/Lauren, Rachel/Finn, Tina/Mike,
Other optional Glee pairings: Rory/Sugar, Jeff/Nick, Mercedes/Sam, Will/Emma, Carol/Burt~~~~~~~~~~~Preferred Harry Potter pairings: (if following strict canon): Hagrid/Olympe, Cedric/Cho
(if changing things up): Harry/Ginny, Hermione/Ron, Cedric/Cho, Lupin/Tonks,
Other optional HP pairings: Neville/Luna, Fred/Angelina~~~~~~~~~~~BONUSES: Brittany and Luna become friends.
The kids from the American schools believe Harry and offer to help him, leading them to come back later for the Battle of Hogwarts, which leads to less deaths.~~~~~~~~~~~Feel free to ignore any or all of this. The blasted plot bunny would not stop nipping at my heels and I have to go to sleep. So I throw it at all of you. Good luck.