Seeing today's episode, and given the plot so far, w/ Jyoti reluctant to discuss her family w/ her in-laws, there is another way Sudha can attend the wedding, w/o anyone else attending. Lets say that Jyoti keeps this a secret from her family, and Sudha, for a different reason, suddenly turns into Devika in one of the next few episodes, on the night of Jyoti's wedding. She goes to the club, and not finding Uday there, goes to his house just before they are leaving for the wedding, and so he asks her to accompany him to the wedding. So she goes, and there, she, as Devika, sees Jyoti get married.
That's one way to do it. And neither she nor Jyoti really recognize each other - let's say Jyoti/Kalpana spots her, but her constant speaking in English, as well as her mannerisms, convince her that it's not Sudha, while Devika doesn't know Jyoti or Kalpana, and so can't make out whose wedding she's at, aside from Uday's cousin.