Anything could work, but not unless you have excellent writing. You need more than just a genre too. You need to know in your heart of hearts what is the premise of this tale you want to tell. What is the reason that you came up with a tale of orphans in foster care. Unless that idea was just completely random (and if it was, you’re kind of out of luck) then there must have been some kind of interesting premise in you or your brother’s minds when you came up with the idea. How do you want the viewer to feel or react or be moved by this story?
Think of tv shows and movies that have moved you, or meant something to you. What did you like about them? Was it the dialogue, the actual unusual/or odd story? The good looks of the actors? The chemistry and identification with the romantic characters? The brilliant comedy? The twists and turns of an excellent mystery? The incredible moral of the story that became clear at the end? Does a bunch of really interesting stuff happen to the kids, but there’s a huge un-expected twist at the end? Is it a feel good movie? Or is it a movie that portrays gritty, harsh realities? You need to figure it out.
You need to have more than just a simple idea before you can progress. And hopefully you looked at some of the answers on your brother’s threads to see that the “idea” of foster kids and orphans has been done repeatedly. So if you’re going to continue with that idea, you need to have a really fantastic premise as well as excellent writing. It doesn’t really make any difference what genre it ends up becoming, you have to write it the other way around.
Everybody that has answered, and answered repeatedly is giving you excellent advice. If you think everyone is ignorant and you are disgusted, then maybe you should try going to film school and you can pay for the same answers instead of getting them for free. Or get 20 of your closest friends together and brainstorm for a few months and see if that helps.