I have a question. Actually, this is not really related to Krishna or Mahabharat actually, but I think the answer may be in MB more than any other purana.
I found out the other day that in regions where cousin marriages are still done, there are restrictions on them. As per our scriptures, cousins cannot marry if they are the children of two sisters or two brothers. A boy's mother and the girl's father either have to be siblings, or the boy's father and the girl's mother have to be siblings. However, I also learned that there is a restriction within that and that cousin marriages generally do not happen between a brother's son and a sister's daughter, and that it must be a brother's daughter and sister's son marrying each other if cousin marriage is done.
Are there any instances in our puranas of cousin marriages being done between a brother's son and sister's daughter? I know of a few marriages between a sister's son and brother's daughter, like Subhadra and Arjun's marriage, but I've never heard of the other way (a brother's son and sister's daughter).
I'm just interested to know if there are such instances if anyone knows...in South India, it's called eduru menarikam and generally people look down on those, though cousin marriages between a brother's daughter and sister's son are accepted.