When the Local Rep is logged in, they can input the Email of Client. Use the action ‘Create an account for another user’. This will create an account for your client.
Then the Local Rep can add further details to create inventory etc which you need to ensure gets linked to the client user.
Send an email to the Client when their account is created asking them to reset their password. Or you can use magic link.
Client can then access all their store details.
Here in the privacy rules, ypu need to ensure some hierarchy. Client sees their data, Local Rep sees data of the Client they added, Admin sees all data and so on.
Hope this helps.