Is it rude to ask for guest addresses?

I’m in a weird situation and need advice. My brother got married recently and I remember his wife (my sister in law) sitting at my aunts house digitizing our family’s addresses for her invitations. My aunt has maintained the entire extended family’s addresses over the years and is usually the go-to person. The problem is that she records everything in a handwritten notebook from a decade ago and tries to cross out old addresses, add new ones, etc and it’s a nightmare to read.


So my sister in law had to spend a ton of time manually going through hundreds of addresses and adding it onto her computer. Anyway she was able to complete this daunting task and frequently mentions how she updates it regularly on her computer.
My older sister is now engaged and im helping her by compiling all the addresses for our family. I remember my sister in law has this amazing list, so I asked if she could share it with me. She never replied to my message, which I found weird. I saw her about a week later and brought it up again, thinking she just forgot. She made a weird excuse to end the conversation and moved on. About a month passed and I really needed to get this list going, so I just called her up and asked for the list a third time. I was really polite and thought this was a normal request?
But she said she won’t be sharing her address list because of how much work she had to do to create it, and now everyone else just gets to use her hard work. I was not expecting this and didn’t quite know what to say, so I just got off the phone quickly.
Was it rude that I asked for it? Am I missing something? So I’ve been back trying to translate my aunts handwriting for myself and no one in the family can understand why we can’t just have the list. Am I doing something wrong here?