How can I get family members (grandparents, aunts, etc.) to stop speaking to my 3.5 year old in "baby voices?"

I feel like we all expect her to act like a grown up in certain situations like restaurants, public places, the dinner table and in many other situations. They treat her like a baby, speaking to her in this irritating squeaky voice that my wife and I find really bothersome. Anyone else deal with this and how did you get people to stop doing this? It's incredibly annoying and I can't quite articulate why but I feel like it's not good to treat her like that, it's like she's some weird mascot or a pet or something. I feel like she deserves a little more respect than this and if we expect her to act properly in social situations this doesn't seem to help matters. Any insight is appreciated. via /r/Parenting http://ift.tt/2bjm05H