An idea from Guest:
Another interesting spy-girl story you might like to cross with is a movie (not that great, but not totally bad either) called "Barely Lethal". It ahs star-power in the cast, but also a rather formulaic script. But that's fine, cause that makes crossing over easy.
It's about a teen spy who fakes her own death so she can live a normal life. But her old employers find out and send her rival to retrieve her. She goes to school, falls in love ... so yeah, everything you'd need elements wise to plug Miraculous in. (Not sure how Kwami and superheros fit).
Marinette is the hero. Chloe her rival. Alya and Nino, as siblings (and using Alya's mom Marlene and her dad, the zookeeper, as the parents) could be the family she ends up staying with. Adrien is the love interest.
Whose Who:
83/Megan - Marinette
84/ Heather - Chloe
1/Victoria Knox - Lila
Hardman - Master Fu
Liz Larson - Alya
Roger - Adrien
Cash - Nathaniel/Theo
Parker Larson - Nino/Manon
Gooch - Nino
Mrs. Larson - Marlene Cesaire