Does anyone know if it is alowable to connect a wc, basin and shower via a macerator in either 32 or 40mm into a 3" soil stack/vent as the connection to the 4" part is no longer accessible.The 3" stack is conected directly into and above the 4" and is a single stack system with no secondary venterlation, the building currently has only one wc and is 2 storys high soon to be 3 with this loft convertion.