YA Fantasy about a commoner girl who moves into a castle and becomes the singing voice for the prince’s betrothed. Read 2010-2011.

[Jasmine]

This would have been read in 2010-2011. Singing is highly valued in the royal family, and the betrothed is using the FMC as her ventriloquist to trick the family into thinking she can sing. The main character and the prince end up together, and I also vaguely remember an underground resistance force. May have been a series?

[Merannda]

Fairest by Gail Carson Levine?

[Kris]

Google Books preview of Fairest by Gail Carson Levine - Merannda's suggestion:

- https://www.amazon.com/Fairest-Gail-C...
- There are different cover images.