How to Restrict Customer (Party-Level) Data Visibility by Business Unit

Hi,

We have a requirement to restrict visibility of customer (party-level) data based on the business units that users are assigned to. For example, if User 1 has access only to Business Unit A, they should be able to view only those customers that have accounts or sites associated with Business Unit A.

Additionally, User 1 should not be able to search for or access any customer information that belongs to other business units, including the party-level information.

Could you please advise whether it is possible to configure such restrictions using custom security access, or if there are any alternative approaches or workarounds to achieve this requirement?