You don't need to add Alexa to a routine to control it with your voice - routines and many devices work with Alexa's voice commands after connecting Yonomi.
Each time you add a routine, change the name of a routine, or connect a new device to Yonomi, you’ll need to refresh the Alexa’s integration by saying “Alexa, discover my devices.” Wait for Alexa to finish discovering your changes, and then you're all set.
You can activate a routine by saying “Alexa, turn on <Routine Name>.”
Some devices can be turned on or off as well. Look in the Connected Home section of the Amazon Alexa app to see what devices Yonomi shares with Alexa.