To get more inputs, there are a few options. You can add either:
DCEXI-16D 16 Input Expansion Module
This connects directly into the DALI CONTROL Line controller and provides an extra 16 Inputs. It does not require a DALI address.
DCDALIO-0402 4-Input Module
This is a mains powered device that connects directly to the DALI Line. It requires 1 DALI address. As the DCDALIO-0402 must be programmed via a DALI CONTROL Line Controller, it is normally not used as a stand-alone device.