Madonna and Leon had a brief romance in the 1990s and have both been actively raising Lourdes, their only child.
The teen has been dating "Homeland" actor and her LaGuardia High School of Music & Art & Performing Arts classmate Timothee Chalamet for months.
"You would think Madonna was the stricter parent, but she's actually loosened the reigns because she trusts Lourdes so much," a source close to Leon told RadarOnline.
"On the other hand, Carlos is the watchful dad who's laid down some very stern ground rules for his precious daughter. Madonna was the villain because she was very firm when it came to school studies and manners early on, but that's changed as Lourdes has matured.
"Now she secretly gets a kick out of it when Lourdes complains to her about the curfew her dad's imposed and all the embarrassing questions he asks her and Timothee. For a change Madonna is not the mean parent!"
Madonna, 54, also has a son Rocco, 13, from her former marriage to filmmaker Guy Richie, as well as two adopted children -- David 8, and Mercy, 7.