SOLVED. YA / Kids book about a girl who makes friends with ghosts in a theatre. [s]

[Amelie]

im not sure what parst of this description will be spoiler because i cant remember when the events happen in it but spoiler warnig just incase

so i think i read this in like 2015 but im not 100% sure it seemed like a modern book at the time so im thinking probably published in the late 2000s to 2010s. the main plost i think was this girl who family was renovating this old theatre in the summer, she meets these people and they tirn out to be ghosts ( im not sure when this is revealed) she spend the whole summer talking to them and in the end i think it turnes outbthat shes actually a ghost as well. im pretty sure this happens relitivly close to the end but there definatly a part where sh tries to talk to her parent at some point but i cant remember what happens.
i know its pretty vague but i just remembered about this book and i cant find it anywhere.

[Amelie]

also im pretty sure they all died because the theatre had black mould

[Kassy]

The Positively Last Performance?

[Amelie]

yes omg that it!! tysm imma relive me childhood rn and reread it :)