I have an aquaero 6, but do not have the farbwerk or power adjust, so take my comments with a grain of salt. I know there are knowledgeable folks who frequent this forum that will hopefully jump in with their thoughts.

Looking at the farbwerk introduction thread section 5, it appears you can have two farbwerks connected to an aquaero 5:

Quoted

5.) Control by aquaero / aquabus
Naturally, the farbwerk is another big player in our aquabus network. Each single channel (there are three per RGB channel, 12 in total) can be controlled by the aquaero as a dedicated channel. In the course of further development the RGB controller of the aquaero has been improved significantly and allows to control the channels of the farbwerk. The channels can also be controlled by sensors of the aquaero.

The new aquaero firmware 2000 can connect to two farbwerk units which means up to eight RGB channels respectively 24 outputs can be controlled.

The poweradjust manual seems to indicate various connection are available including the aquabus which communicates with the aquaero.

The high-flow-sensor looks to be able to connect to the poweradjust or the aquero.

You would benefit from reading the aquaero manual and searching for powewradjust to see important information.

There are multiple versions of each item you mentioned, so to get a more specific comments it may be useful if you specified the model or item numbers of each item.

Each MPS device type has a set number of addresses available on the aquabus, and each MPS device needs a unique address. If you look at section "25.1 Compatible aquabus devices" in the aquaero manual you will see a table that lists the devices in the left column, and the corresponding right column shows the addresses available.