I don’t know the coalition app so i’m not sure about this but there is a hack you can do with the common app. Fill out the common app for the dream school. Put whatever you want in there as far as your essay, how you describe your ECs, particular references that you think might score with that school, etc. When you turn it in, you’ll see “submitted” next to the school name. Now wait for it to say “downloaded” (that can take from a day until a week). Once that has happened, it means that the school has downloaded your application and the common app part is over for them. NOW you can go back in and change whatever and then begin submitting to the new colleges.
(but noting again that I don’t know if this works with the coalition app).