Is there any legal complication in doing court marriage with Rakhi Sister

is there any legal complication in doing court marriage with Rakhi Sister ? actually she was tied me rakhi 10 yrs ago bcoz i was his brothers friend... now we felt extreme love for each other and want to marry.... but her parents r not ready.... now we want to go for Court Marriage... is this legal or not ? her parents have some pictures of us in which she was tying me Rakhi.... kindly help me