Hi Calambai,
Thanks for reaching out here in the community! I'd be happy to assist you with your concerns regarding how to transmit a song from your smartphone to each of your three Nest Audio speakers in your three separate rooms.
In this case, the best option is to set up a speaker group, which will enable you to play music on all three of your Nest Audio devices simultaneously in each of your three rooms if they are under the same home structure in the Google Home app.
To create the speaker group, please refer to the next article for guidance: Create and manage speaker groups in the Google Home app.
Let me know if you have more questions.
Best regards,
Jenniffer
