Hi,
In OData, repeated properties are referred as collections of entities. Therefore, in your OData model you need to represent the address property of the original REST service as an entity and create an association between the main entity ("register" in the original REST service). This might require you to define additional key property(or properties) in the newly created address entity, so that you satisfy OData requirement that each entity must have a unique key and also to establish the association with the main entity.
I hope this helps.
Regards,
Mustafa.