As we all know, Kate was at Roman's wedding in the revenge ending, but it turns out her model is present during the deal wedding! She has her own set of animations, but she spawns under the map, making her unviewable in normal gameplay. You have to view the cutscene with OpenIV to see her spawn.
So it turns out she was gonna be in both weddings. Weird, isn't it? Especially considering that her animations suggest that she didn't try to talk to Niko. She actually just STARES are Roman's body!