How should I repair communication between my sister and my parents?

My sister is getting married next summer to a guy with a different culture, and it sounds like their wedding will be mainly following his cultures wedding traditions. I have no objections because it's not my wedding, and as long as my sister makes sure that there are accomodations for our side (like food that's not too spicy, dietary restrictions are met), I don't care what she plans and will wear whatever outfit she puts me in. The problem lies with my parents. My sister and her fiance only talk about his cultures elements to my parents, which makes them feel like our culture is underepresented, and possibly like they are losing her to his family. I told my sister that my parents were feeling the first part, and that she should mention some of our cultures elements that will be included when she visits. She has yet to do so, and my parents also aren't asking anything about the wedding due to her getting upset when asked about it before she met his parents. So I'm the only one asking her about the wedding, what elements from our culture that she wants to include, what the elements from his culture are, etc. When we talk about this stuff my parents either aren't there or aren't listening, making me feel like I'm in the middle of a stupid telephone game. The other day I told my parents to try to communicate with her more and ask her stuff and relate their feelings, but I feel like they won't. My sister is coming over tomorrow and staying for the weekend, and I feel like neither party will try to make a line of communication. I'm sick of being the only one communicating with anybody, so what should I do to help them establish a line of communication? Sorry for the rant, I'm a little upset by all this.
How should I repair communication between my sister and my parents?
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