Huh. Correct me if I'm wrong, but from Alice's reaction it looks as though Marisa isn't on very good terms with her family.
This is true in both this story and in canon. Marisa ran away from her home, it was never mention why though.
Hmm...If you're saying things like that, you must have an idea, right, Alice?They should arrive today.That shop has some ridiculous security.For the time being, I've decided to get some ingredients sent from my home.Propose that concrete plan of yours right this moment!...Ah! Marisa... I mean...What to do to sneak in there...Write them a letter or something at once.Well then, I guess I should ask Remi.
See: Three Plus One + Remilia Sakuya