Apparently there will be another solution later on playable day 17. Which will be a difficult solution. So if Sophia does not accept Morello's help, the Aiden storyline continues. If she refuses in between then ofcourse the Dylan route ends.
How I theorize the events will play out is :-
Sophia will do or not do the task.
If she does not, then Dylan is sent to the boarding school as usual.
If she does, then at the end of the task, while she reflects on what she did, she will have the thought of asking Morello for help.
Hence why we have the Morello event as Optional. If she takes his help, Aiden is dealt with plus a scene with Morello.
If she decides not to take the help, then things will stay just as usual.