Your institution should have decided, based on a risk analysis, what it would consider as "owner" for purposes of CIP. Some banks have set a 10% ownership threshold. Others have set higher, and others have set it lower.
The KYC/EDD/AML information should be on the customer as a whole, the source of funds, the nature of the transaction, and any other considerations for money laundering risk. For real estate deals, you need to be satisfied that you are dealing with legitimate funding from the customer. IOW, you do not want to have a construction loan where the borrower's equity came from laundered money.
_________________________
CRCM,CAMS
Regulations are a poor substitute for ethics.
Just sayin'