Amendment of settlement deed

Once settlment deed executed,  amendment settlement is not valid.

If you want,  your sons shares. Yours sons can execute the another settlement deed in favour of you or your wife.

Adv Sumathy is right in opining that the settlement deed once executed and acted upon cannot be revoked for any reason unless the condition implied therein have not been complied with and should that non-compliance be a ground for revocation of the said deed.  Further, if you want the property back on your name, the share holders have to sell their respective shares in the said  property to you by executing a registered sale deed in your favor, re-settlement deed is not a legal term hence your sons cannot re-settle the property in your name.