You have two options to connect one Dimwheel to multiple decoders.
Option one, the easier way to connect them, is to connect one Dimwheel to one decoder’s DMX IN. Connect the second decoder by connecting its DMX IN to the first decoder’s DMX IN. Repeat this for each decoder.
Option two is to connect a separate wire from the Dimwheel to each decoder. This can be difficult depending on the number of decoders you have, and the number of wires you need to fit into one terminal.