Make her more suggestible.

Your really horny after all the stuff you've learn this week and now you want to use you knew knowledge.

She drinks it with no apparent change and then after breakfast she prepare the first lesson: how to walk in heels.

As you learn how to walk you try you first suggest

"maybe after this we could move on to corsets"

"great idea" she says

Then

"hay why am I the only one dress up here, you should be in a corset and heels too."

"why not?"

"here let me help you with that"

You give a might tug on the corset and both you a Hermione gasp. It looks like that little extra always lubricate potion came in handy, because some how your penetrating Herminone's ass. It must be the stocking it gose throughout everything but flesh.