Leah didn't know the right move. But she knew what she was about to do was the wrong one. After a moment, she swallowed the pill. There were a few reasons behind her decision. First, she didn't want Rita to get suspicious in any way. She didn't want Rita to find the pills, and even if Rita didn't know what the pills did (as seemed to be the case), Leah suddenly having zero accidents after last night would raise eyebrows.
Second, Leah was feeling a bit vengeful. If this was what Tina wanted, this was what she was going to get! A poopy diapered teenage stepdaughter.
Third... Leah sighed. She'd heard Tina talk about potty training before. When a kid regressed, they had to go all the way back to get properly trained. Leah...sort of wanted to finally get potty trained. If it meant becoming diaper dependent, so be it.
But she was going to use the bathroom while she was there. Leah removed her diaper and sat on the toilet. Then, she relaxed. A mountain of shit came out of her. She winced. Rita might need to buy thicker diapers for her.
Once she was finished, Leah wiped, washed her hands, and put her diaper back on. She then strolled into the living room, ready to start her first day of what she was going to call diaper training.