Step daughters/Asexual/1st Wednesday/play here
"Hey you" you say greeting Sandra with a big smile. You put your hands under her arm to lift her up and make a turn on yourself with her.
Sandra, happy and excited: "Youhou!".
You greet Masha with a "Hi" which she does not seem to notice.
You, asking an already excited Sandra: "Are you ready to fly?"
Sandra: "Yeaaaah"
So you lift her up and down a few times and then make her fly in the room (held the whole time of course) doing plane noises.
Sandra laughs and is happy but soon Masha Shhh you, trying to focus on the tv.
Now you could go play with Sandra in her room still, go behind the sofa so Masha would not see you ... or sit right next to Masha and put Masha on your lap.