Thanks Tom for your help it works fine now.
What we did was:
We have a 'Name' business object and a 'Property' Business object
There is a relationshhip where a 'Name' can own one or more 'Property' and a property can be owned by one or more 'Name'
We then defined a new 'PropertyName' business object which is a normalisation of this many to many relationship. We put a relationship attribute on 'PropertyName' to record either the 'Owner' or 'Occupier' relationship between the 'Name' and the 'Property'
The 'Name' attribute on 'PropertyName' is defined as 'Peer' to 'Property' with out multiples allowed.
The 'Property' attribute on 'PropertyName' is defined as 'Peer' to 'Name' with out multiples allowed.