sister not including wife?

hi my sister is getting married and she lives in my home with my wife and dad. she has not been involving my wife or introducing her to the guy side yet she had introduced everyone else like my sisters. She is inviting the guy side over and she has asked my sister who lives in other home to coordinate the details like date and time. my wife tells me she is pissed off that she has not let her talk to guy side for cooridnating these details. she said she wont cook anything for them because she feels like she is a servant. when i ask my sisters to please involve her. they get upset at me saying that sister in law dont get involved in these things. are they right or is my wife right?