Applicability of Mitakshara Co-Wife's Right vs. Contract Law - Tricky Territory

I remember this question from last year's AILET PG paper: "A woman married under Hindu Marriage Act is entitled to the limited estate under the Mitakshara school. Whether in such a case, her right of co-parcenary can be waived by a contract with her co-owners in a family property, given that Hindu Succession (Amendment) Act, 2005 abolished the right of co-parcenary for women?" Okay, so here's the thing - initially, it seems like two separate concepts, contract law and the Mitakshara co-wife's right are colliding. The key is to see it from a historical perspective: what happened pre and post the amendment, and how did the Supreme Court interpret this in the case of Shyam Singh vs. Smt. Shyamlata.