Spies In Paris (Miraculous Ladybug/ Highschool!Phineas and Ferb)

AU where Phineas and the gang become spies at O.W.C.A after the second demention, fast forward 7 years and with Doctor D. and agent P on their team they engage in their first forgen mission.
French secret service is getting worried that Ladybug and Chat Noir are too preoccupied with the nearly day- to day akumas to put much effort into uncovering Hawk Moth, so unbeknownst to the heros they enlist the help of their allies O.W.C.A in the colonies.
While Dr. D (codename Agent O) and Perry (Codename Agent P) try to get in close with Hawky, Phineas (Codename Agent H.P.), Ferb (codename Agent H.F.), Baljeet (Codename Agent Little H.B), Buford ( Codename Agent Big H.B.), and Isabella (Codename Agent H.I ) get placed in France Depot Highschool to get to know the kids and try to figure out what the heck is going on.
Why are Marionette and Adrien always disappearing? Why do they get nervous when Ladybug and Chat Noir get mentioned? Who are Ladybug and Chat Noir? Why is Hawk Moth preying on innocent people?
With orders not to engage until Doof and Perry report back the gang can do nothing but wait. Or that's what they should do but they were never. very good at following rules.
Takes place pre Volpina.

****Disclaimer, I don't own any of these shows or their characters. I only own the plot****