(15)In the case of master-feeder structures, the description of the feeder UCITS’ risk and reward profile should not be materially different to that of the corresponding section in the master UCITS’ key investor information document so that the feeder can copy information from the key investor information document of the master wherever it is relevant. However, this information should be supplemented by relevant statements or duly adjusted in those cases where ancillary assets held by the feeder might modify the risk profile compared to the master, addressing the risks inherent in these ancillary assets, for instance where derivatives are used. The combined costs of investing in the feeder and the master should be disclosed to investors in the feeder.