Hey You! Yeah You again, thats scrolling though the comments, I need your help again with this plot thingy!

So this is an idea that I thought about a few months ago and got developed with the help of my two friends, Mckapo and kat_I_Am. Unfortunately, it was put off due to a very devastating writer's block and.. some procrasination and school. However, my writer's block has gone away for the time being and I have gotten into the swing of writing
Alright enough boring backstory and onto the idea

THE IDEA

There's an old mansion hidden within Earth. No one has ever found or even known about it.
UNTIL
NOW
a group of teenagers, go on a field trip through the forest before they get separated from the main group when what seemed like a savage animal attack occurred. Which forced the teenagers to run deep in the forest, stumbling along the mansion. Assuming it was abandoned, the teens decided to take shelter and try to find ways to get help, as they explore the mansion, they find a basement containing lots of doors, all looking different from each other. It turns out these doors lead to our fairytale worlds, Wonderland, Camelot, Neverland, Un-named fairytale land, OZ, and well our little Earth and soon to be explored space. There will also be some small, but major realms like the Dark Realm, the Dream Realm, and all that jazz. But Narrator, what does this have to do with the story? I hear you asking.
Dun dun dunnnnn
Well you see
Well
Um
well…
Ok I haven't figured out this part yet, but there's an ongoing war between the realms, leaving Oz neutral, but tensions high, forcing some famous characters to somehow. escape to Earth where they give birth to their children which are the key to reuniting these worlds again.
Who are these characters? You curious readers still continue to ask?
Well they include
One Daughter of red riding hood
one son of Captain Hook
One daughter of Alice
One normal kid who somehow has powers
One son of Glinda the good witch
And I think One son of king author
Basically

Sharpshooter
Hi I'm Chirs I'm so Emo
Girl Power
Tech Z
Fairy Godfather
Nerd Boy

So anyway, I guess this is going to turn into a series
because
well I forgot to explain this earlier
So basically the war was started by an evil dude so he could take over
Also I'm going to have this one really powerful amulet, but it was shattered by the dude so… yeah
each piece is in each major world listed above
and then they have to find all the pieces and defeat the dude using the power of magic

So what is it that you want help with/ are stuck on/ dont know what to do?

So
I kind of need help with the conflict between the realms
travel between realms without the doors
conflicts for each piece of the amulet
the bad guy duh
and the animal that attacked them was actually a guardian of the Mansion
so that
and more that I'm forgetting

I would soooo read this story if I found it in the library (aka my happy place)

Aww thank you

okay, so, portals first. you can give the characters portals that show up where they can jump between worlds. maybe these are used by the rouges of the different lands to travel to different lands and steal artifacts/ smuggle things/ go to some fancy trade place to sell them for money. or maybe you give them all objects that can help them travel (think portkeys from Harry Potter).
if each character is going to be retrieving an amulet piece, give them a conflict that plays to their weaknesses. for example, give the "nerd boy" son of king Arthur, a knight that he has to battle. After he battles it once and discovers that there's no way that he defeats it on his own strength maybe he tries to beat it by outsmarting it with street smarts or simply befriending it or something instead of battling it directly.

If you don't know what kind of animal you want, (obviously an evil/scary one) you could always go with the stereotypical black dog, or you could look for a more creative one. Like a goblin. a ghost, a banshee, a gargoyle or even a creepy talking (magical) plant that startles them and chases them into a different dimension by growing bigger/ taking over the room.

Or alternatively, (and i know this isn't what you were wanting, but you could consider it if you are really stuck) the one character who is the most daredevil of the six, maybe the son of captain hook who has always wanted to go on adventures like his father or something, is all like, "i'm gonna do it… i'm gonna go inside, it looks like fun!" and some of them are all like cool but like two of them go all like, "You are so stupid you're gonna get killed and that's not the way out. that doesn't even look like earth, the plant looks poisonous" etc but they get dragged along because now someone responsible should go keep them safe.

okay, moving on to the bad guy, why does he want to take over/ what is he doing? is he treating the different dimensions harsher than others, causing conflict? Has he only taken over some of them? this will increase the stakes and make it easier to build conflict within the book. He can send his minions to the different realms to take over village by village where they encounter the protagonists. the protagonists hear stories of them when they first arrive and are still surprised to see them. that sort of stuff.
maybe the antagonist is a child of a long forgotten villain that curses all the realms for destroying their family when they were only a child and has decided to take over to get revenge on those who hurt them and make them feel what they felt/ make them understand. this could make them a fitting conflict.
also, consider, do your characters know that their parents are the people in the stories? do they go to some secret magic school? are they typically forced to hide their powers and not know who the others are? this will influence the dynamic and how they respond to the antagonist.
the antagonist could see themselves as a hero, see themselves taking over as being gracious because they will eradicate poverty…. by killing half the population or something.

That's all I got for now. Hope it helps! Good luck with your writing!

I just remembered one of my questions

so for the doors, they're like legends, so no one has actually found them, but all the parents of my characters have.
So I don't know how to make that work.

if the parents only talk about them to their kids like legends it should be fine.
a good example of this is in The Lion the Witch and the Wardrobe by C.S.Lewis. one of the kids finds Narnia and tells the others who don't believe her. the oldest two siblings go to the owner of the house (a character who has been to Narnia before, but shhhh they don't know that) tells them that maybe their sister is right. maybe she has found something.
he is super mysterious about it and i'm not sure how helpful this was but I tried.

also yeah, I agree with @Bremston I would definitely read this :)

I just remembered one of my questions

so for the doors, they're like legends, so no one has actually found them, but all the parents of my characters have.
So I don't know how to make that work.

When I mean legends, I mean legends in the realms so no one has access to them. The kids don't even know about their heritage, And I have I good idea for my Earth kid Zoe. Anyway, should I make the doors, appear like once every something-something
or like maybe theres a spell?
Wow depression really makes you brain dead.

Oooooooooohhhh, okay. that sounds even cooler that what I was thinking.
Well, honestly something only appearing once every one hundred years or something is a decent reason for a generational gap and for not so smart teenagers to go exploring before getting completely separated from the group, or something so I don't see why not.
don't worry about being brain dead too much, my dude, everyone gets stuck.

Lol ok thank you!
I will ask if I need anything