Based on the provided legal document, the key points are as follows:

1. The case involves a dispute over inheritance rights among the heirs of a deceased Muslim individual, where the question is whether deeds of relinquishment executed by heirs during the lifetime of the deceased can operate as estoppel to claims made after the death of the owner (!) (!) .

2. The doctrine of 'Spes Successions' under Muslim law and the Transfer of Property Act indicates that a chance of inheritance cannot be transferred or relinquished during the lifetime of the owner, as such rights are considered inchoate and not vested (!) (!) .

3. The law recognizes that a Muslim cannot legally relinquish a future share in the estate, as inheritance is only open upon the death of the owner, and such relinquishments made during the owner’s lifetime are generally null and void, unless certain circumstances, such as consideration or estoppel, apply (!) (!) .

4. The concept of estoppel can apply if an heir acts in a manner that suggests they have relinquished their expectancy, especially if they have received consideration for such relinquishment, which can then prevent them from later claiming their share (!) (!) .

5. Family arrangements or settlements that are made during the lifetime of the owner, which involve the relinquishment of future inheritance rights, may be recognized if they are made jointly by the family. However, individual deeds of relinquishment executed by heirs are considered separate agreements and do not constitute a family settlement (!) (!) .

6. The law emphasizes that a deed of relinquishment during the lifetime of the owner, especially when executed unilaterally and without mutual consent, does not create a valid transfer of a future expectancy unless supported by considerations such as estoppel or public policy considerations (!) .

7. The courts have held that relinquishment of a future inheritance right during the owner’s lifetime is generally invalid under Muslim law, and any attempt to do so can be challenged on the grounds of public policy and the principles governing inheritance rights (!) .

8. The doctrine of estoppel, as well as principles of public policy, prevent heirs from claiming a share in the estate after relinquishing their expectancy during the owner’s lifetime, especially if they have received consideration for such relinquishment (!) .

9. The case underscores the importance of understanding the legal principles governing inheritance under Muslim law and the Transfer of Property Act, particularly the restrictions on transferring or relinquishing future expectancy rights (!) .

10. Ultimately, the court dismissed the special leave petitions, affirming that deeds of relinquishment executed by heirs during the lifetime of the owner do not operate as valid transfers of future shares, and the heirs are estopped from claiming such shares after the owner's death (!) .

These points collectively highlight the legal stance that relinquishing a future inheritance during the lifetime of the owner is generally not valid, but may be challenged or upheld based on considerations of estoppel, consideration, and public policy.