Tell Tanya you can finish this yourself.

"I think I can handle it from here." You tell Tanya, eager for some privacy with Sarah.

"What do you think Sarah?" Tanya asks her friend with a knowing smile.

"We'll be fine" Sarah agrees, anticipating what you have in mind.

"Okay." Tanya turns to leave. "Come get me if you need any help."

As soon as she has closed the door behind herself you separate her labia and wipe firmly between them. Sarah moans again, much more loudly as you rub across her clit.

"I'd better make sure this is very clean." You keep rubbing it.

Sarah starts grinding against your hand, her bottom moving backwards and forwards on the soggy padding of her diaper.

You feel your cock straining agaimst your underwear. It demands some attention too.