If you have delegated responsibility for handling abuse to a customer for the part of your network they use, they need a similar set-up to your own. Either you can set this up for them, if you maintain all the RIPE Database objects, or they can partly set it up themselves. However, in most cases, you will maintain the inet(6)num assignment objects, so you will have to add the organisation reference to these objects.
You first need a role object for the customer and it must contain an "abuse-mailbox:" attribute. If the customer already has one, you can use that one. Otherwise, you will need to create a new one. This role object does not need to reference any person objects. It will be public with no query limits, so all information it contains is assumed to be business data, not personal or private data.
When creating a new organisation object with "org-type: OTHER" or editing an existing one using Webupdates, you will be able to search for an existing abuse role account in the "abuse-c:" attribute, or create a new one seamlessly.
Finally, reference this organisation object in the customer's assignment object(s). Any query for the customer's IP address(es) will now return their abuse contact details instead of the contact details you set up for the parent allocation.