I'm interested in how sending works in relation to characters disguising themselves as someone else.
Let's say you make up a false identity - Mr. Goodweather - and make some friends. One of those friends tries to cast sending to Mr. Goodweather.
Does the spell
A) connect to you, because your friend intended you as the recipient?
B) fail, because there is no such person as Mr. Goodweather?
Take this a step further. Instead of a false identity made up, let's say you stole someone else's identity - Mr. Fairweather - and pretended to be him. You meet some people who have never met the real Mr. Fairweather, so in their mind, you are him.
One of those people casts sending to Mr. Fairweather. Does the spell
A) connect to you, because you are the person they intended as the recipient?
B) fail, because the caster isn't actually familiar with Mr. Fairweather? They've never even met!
And to add another level of complication, let's say your friend from the second example later gets to know the real Mr. Fairweather but remains ignorant of your deception. He has no idea that you and Mr. Fairweather are different people. As far as he's concerned, the guy he knows today (the real thing) is the same person as the one he met originally (you). He has something to tell Mr. Fairweather and so casts sending. Does the spell:
A) connect to you, because you were the one he first thought of as Mr. Fairweather?
B) connect to the real Mr. Fairweather, whom he knows now?
C) fail because of buffer overflow error? (caster failed to select a single target)
D) randomly connect to either you or the real Mr. Fairweather based on things like
- which of you is physically closer to the caster
- which of you is more familiar to the caster
- which of you the caster dealt with most recently
- other
Now in the other direction, if you're familiar with someone and a bad guy impersonates them and fools you, it seems logical to me that a sending would go to your real friend and not the imposter.
But what if your real friend was dead, and the imposter completely fooled you. Would sending now connect to him, or fail?
Mmmh... There's no mention of name in the Sending spell description... The spell state "You contact a particular creature with which you are familiar and send a short message of 25 words or less to the subject. The subject recognizes you if it knows you.", so you don't have to state a name just think of a person.
- point 1: A. There is such a person as mr. Goodweather, both in the mind of the sender as well as in the intended recipient.
- point 2: A. The caster has met a mr. Fairweather, albeit in the form of your impersonation. As long as you keep pretending to be Fairweather, Sendings from your fake Fairweather friends (see what I did there?) should arrive at your mind.
- point 3: Tricky. The previous answers are both based on the premise that a created identity is as real as a "real" one, but that just makes this question harder to answer. A and B are possibilities. I'd disregard options C and D. C falls outside the established rules for magic and D just creates more questions. My suggestion would be E: the spell connects to both Fairweathers, since they both are Fairweather, and "Fairweather" is one, single target (even though it's portrayed by two persons). This allowes subterfuge to go unnoticed for longer (which is a good thing in most games), and creates funny situations if both Fairweathers reply.
- point addendum: as long as there is a person who is, as far as you're concerned, "your friend", a Sending should arrive.
The above is 100% my own opinion - I don't think any actual rules cover this (rather interesting) situation. But really, the answer should always be: "Whatever is the most fun for the players and the GM".