How do I find myself in sticky situations?

I seem to find myself in these types of situations often, and I'm not sure I know how to stop getting into them.

For example, last week I get an email from a former co-worker. This is the gist of our email conversation (over several days.)

Her: A new co-worker of mine needs some supplies...can you help with that?

Me: Let me check around the school and talk to my principal...but probably.
(I email my principal and receive a "let me check with someone else and see" response.)

Her (several days later): So what's the word?

Me: Not sure, still waiting to hear. I'll ask again.
(I email my principal again. She says she hadn't heard from the person she was trying to contact, but 'sure, go ahead.')

Me: I can bring 'em!

Principal: Please fill out paperwork before you leave with them.

Me: Okay

Assistant Principal: Has former coworker talked with her principal. We don't want to step on toes when our assistance is not wanted.

Me: Ummmmm... I don't know.

AP: Oh.

Me: They're not even for her...they're for another grade level.

AP: Rolls eyes..."great!" This is not about the supplies. Take them. We want to be helpful. However, we don't want to hurt the development of her relationship with her principal.

Her: Awesome! Let me check and see what their procedures are and see if they still want them!

Are you confused yet? ME TOO! How does one little email turn into a mass CC convention that includes more people with more opinions and thoughts on a subject when it doesn't even affect the two initial emailers!?

UGH! The really tricky part is going to be if they don't want them and I have to go to my AP and principal and say "nevermind."