She throws a "fit"

Of course Natalie wouldn't normally be against this however the thought of her former classmate spreading her legs and exposing her shaved pussy turned her on but also deeply humiliated her. Unsure of what to do and not wanting to pussy out so early she starts kicking her legs softly at Kara.

Kara: "Hey your being a very bad girl if you keep this up your gonna get a timeout or even a spanking." She gently scolds Natalie. Despite the intention being to get Natalie to stop all it did was plant a new idea in her mind, one that blew her arousal way past her shame. Continuing to kick her legs (and doing a bit of mind manipulating) she's quickly set on top of the changing station hands down ass up.

Kara: "I tried to warn you but you've been a very bad girl." As she says this her first blow lands on Natalie's padded back side. Despite how much Natalie was enjoying this she couldn't help but be bored, a gentle spank on her diaper every couple of seconds meant that she wasn't feeling much. Deciding to take things a bit further she uses her powers to make Kara a bit rougher. Feeling the blows come in was night and day compared to how they felt before she used her magic. For every 1 spank she got before using magic 3 would have already hit her bottom by now and that's not to mention how much harder they were hitting, despite the diaper being in the way she could feel her butt get more and more red. With how wet she was the diaper started to lightly sag messing with the angles of the spanking much to Kara's annoyance. Quickly lowering the diaper she gets back to work spanking Natalie much to her surprise. The pain from the bare skin spanking caused her to yell out but the pleasure caused it to quickly switch to moaning. As she came closer to orgasm the spanks slowed and soon after came to a halt.

Kara: "I didn't want to do that but bad girls get spanked. I hope you learned your lesson. Now let's get you changed sweet heart." She says flipping Natalie over. Lifting her legs up Kara quickly takes Natalie's diaper off before spreading her legs wide exposing her soaking pussy. Sprinkling some baby powder on her genitalia Kara quickly reaches down under the changing station and grabs a new diaper for Nicole. Looking at the diaper Natalie could feel her face become even redder then her ass. The idea of being put in the pink, bulky, rainbow plastered diaper she just pulled out was oddly humiliating to her but she couldn't deny the arousal at the thought of people seeing her in it. Before she could contemplate it any further she feels the familiar cushion under her thoroughly used bottom being quickly secured across her waist. Being set back down on the ground Natalie thinks about what to do next.