I have bad news for you.
We wrote the software, and it did not work.
There is something inherent in that blue board, that causes the 3-device configuration not to work.
So, if you need 3 sensors, you are going to have to do the work yourself.
There is nothing preventing you from hooking three satellite boards up directly to the Nucleo.
There is an example in the API that you can download.
And there is an application note.
Connecting all 3 sensors to the I2C is easy - just daisy chain them together. The real trick is going to find out to which pin the XShut pins are connected. For that look into the software and using a schematic of the Nucleo board you can figure it out.
Good luck, and I'm sorry I left you waiting for something I could not supply.
- john