A number of you have asked for a follow-up, "What is interesting mail to a teenager?"
Answer: the latest netflix movie and a lovely thank you card from her Aunt regarding some get well flowers we sent. She is also getting inundated with college materials since taking her PSATs and is always looking for information on colleges.
As for the keys - remember that the in-laws used to live next door. FIL is a regular McGuiver. Seriously. He does stuff like built me a light (the actual light) so that when I open my corner cabinet under my sink, a light magically goes on. And when you close the door, it goes off. And that's small potatoes for him. Anyway, FIL keyed ALL the locks in both houses (deadbolts, everything) to work to one key. And the alarm codes on both houses? the same. Made it easy for us when they lived next door to check each other's houses, FIL could come over at will and fix things (I used to joke about the Fix-It Elf who visited while I was at work - lights in pantries magically appeared, new electrical outlets, etc. Oh he's a licensed electrical engineer...). When they moved out and Ex moved it, it made sense to leave the keys and alarm codes as is so that the kids could move between the houses freely. NO I do not worry about him coming over here. He won't step foot on "my property" as he calls it. literally will not. And He has asked that I "stay off his property." Yes, he is many things, and many strange things at that. But he does have an interesting set of morals and ethics such that I do not worry about him sneaking about in my house.
And yes, I do leave things a certain way and can always tell when someone has been here. But I can also tell that the "someone" is a child....they can't figure out how to come and go without leaving a trail. And that's not a bad thing when they could be trying to be sneaky teenagers!