I have a list of schemes which cover areas of the country based on postcodes and I want to create a polygon feature for each scheme based on merged postcodes within each scheme. However, there is crossover where the same postcode can be included within multiple schemes. If I create the join from the CSV table to the existing postcode polygons, it contains the multiple entries but doesn't provide the spatial attribution. If I reverse the join it doesn't duplicate the postcodes so I don't have the multiple entries.
Any help would be appreciated