I am adding ensuite and building inspector has asked for durgo valve to be fitted internally to toilet soil pipe as length of run is around 5m. The toilet sits against wall and pipe directly exits the back of house and then runs 5m horizontally across to soil stack. What is best way to connect the pipework for the durgo? is there some sort of connector which attachs to the internal part of the soil pipe behind toilet and then branch horizontally to an upright section? There will also be a sink draining into top of soil pipe so is getting a bit crowded behind toilet.