Help needed with selling shares using multiple brokers

So I bought shares on broker A who I do not have POA with so I can’t sell any shares. The shares got credited to my demat account . Now with broker B(zerodha in this case) I have the same demat account linked with POA. So my question is, will I be able to sell my shares from broker B? I tried but it’s not showing under holdings thus I couldn’t sell. Is there a waiting period for my zerodha account to reflect the shares that I bought using broker A?