You're a good sister. One never knows when someone might "cave" into trying new things.
She might gash a foot, or even break a toe, or burn a finger, and you could recommend what she was already given her by you.
I couldn't believe how quickly the pain was relieved with Iodine by both of those examples that I had, upon painting my broken toe and burned finger (by boiling grease).
Amazing.
sometimes it's the smallest thing that opens a person up
And, also, be sure she keeps it in the dark. If she never changes her mind, it'll be there for someone else...it keeps "forever". (I've been known to exaggerate, but Iodine does have a very long shelf-life as long as it's kept out of direct sunlight.)