Scooter Braun's Bringing Sydney Sweeney Around His Kids

Sydney Sweeney and Scooter Braun's relationship is way more serious than thrill-seeking and playing superhero dress-up ... because she's met his kids.

The actress and the music mogul were spotted hopping out of a private jet together at Van Nuys Airport -- a small private hangar just north of Los Angeles -- on Tuesday, along with Scooter's three little ones ... Jagger, Levi and Hart.

Check out the pics ... the party of five walks off the plane as a group and jumps into a waiting car.

It's a quick transition, so we don't actually see Sydney interact with the children ... but she is carrying a small pink backpack that looks like it might belong to Hart, who is wearing a matching sweater.

Unclear when Sydney first met the little ones ... but, it's worth noting, what was first billed to us as a casual relationship turned serious quickly, so it wouldn't surprise us if this isn't their first interaction.

As you know ... Sydney and Scooter have been together for about a year now, and -- despite their busy schedules -- they've found enough time to go on a whole bunch of vacations together, from Australia to Mallorca to Florida.

They've also done some charitable deeds as well ... flying up to Sydney's hometown of Spokane, Washington, amid the devastating wildfires in the area. The two brought food to firefighters between shifts on the front lines and helped prepare meals for families affected by the fires.