No. Don't add milk or alternatives during the steaming cycle.
From the moment you put the smart Moose pitcher onto the machine, Perfect Moose measures the amount of liquid and the temperature to run the steaming recipe accordingly.
That recipe starts running immediately as soon as you place the pitcher on the pitcher holder. Adding liquid during the cycle will disturb this process and will not provide barista quality microfoam.
When there is too much or not enough liquid in the pitcher to start steaming, a message will appear on the display to add or remove liquid. Always take off the pitcher to add or remove liquid. Place the filled pitcher back on and let go of the handle. The device restarts steaming automatically.