1. Since it is under construction it is nt wise to claim your share just now .
2 Your share in safe and the same can not removed form you.
3. You can ask for execution of a common partition deed so your respective shares can be determined early to avid future dispute.
4. In any event you can always claim share by way of filing a suit for partition.
I find execution and registration of a mutual deed of partition is best suited to all of you.