Have you tried reusing the same instance:
RKRelationshipMapping *rkm = [RKRelationshipMapping relationshipMappingFromKeyPath:@"AR1" toKeyPath:@"AR1" withMapping:AR1_Mapping];
[A_Mapping addPropertyMapping:rkm];
[B_Mapping addPropertyMapping:rkm];
...
(If strange things happen as a result then you can copy
rkm
each time you call addPropertyMapping:
.
From your comment, you could write a method to do this by calling propertyMappings
on A_mapping
and then iterating the returned array and calling addPropertyMapping:
on each of the other mappings to 'share' the mappings between each of them.
There is no such thing as mapping inheritance. The mapping instances are each linked to different classes so you can't directly copy them, you can only copy some parts that you use to build them.