07/02/2010 AT 9:20 PM ET
Melissa Etheridge went to court Friday to formally end her partnership with Tammy Lynn Michaels, seeking joint custody of their 3-year-old twins.
In a Petition for Dissolution of Domestic Partnership filed in L.A. County Superior Court, the singer, 49, cited irreconcilable differences and asked that the court not award financial support to Michaels.
Etheridge and Michaels, 35, who had registered as domestic partners in August 2005, ended their nearly nine-year relationship late last year. Michaels gave birth to son Miller and daughter Johnnie in 2006.