Capital gains under Sec 54EC

My siblings and I inherited a residential flat in cooperative society located Mumbai from our deceased parents.

I would like to either relinquish my rights or gift my share, without any consideration in favour of my siblings. My siblings will eventually sell the property and plan to invest the gains from the sale per rules in Sec 54EC bonds.

My questions:

Qs. 1: Would either option that is relinquishment deed or a gift deed, on transfer between siblings attract stamp duty ?

Qs 2: Would each of my remaining siblings be eligible to invest their portion of the "gains from the sale" up to Sec 54EC limit of 50 Lakhs per Assessee? or is the limit of 50 Lakhs per property? They do not have any prior Sec 54EC investment.

Thanks in advance.