Melissa Etheridge and Tammy Lynn Michaels

Melissa Etheridge's ex-partner, Tammy Lynn Michaels, is seeking sole custody of their children.

Michaels, 32, filed papers Thursday in Los Angeles Superior Court requesting full legal and physical custody of their 3-year-old twins, daughter Johnnie Rose and son Miller, besides spousal support, a court spokeswoman told TVGuide.com. Her filing comes a week after Etheridge filed papers requesting joint custody.

Melissa and Tammy Etheridge separate

Both women cited irreconcilable differences, but Michaels — who blogged that she was "blindsided" by Etheridge's filing — filed for dissolution of marriage instead of dissolution of domestic partnership as Etheridge, 49, had. The couple did not qualify to legally marry at the time of their union, but Michaels' lawyer, Steve Knowles, told People that the filing was not a mistake.

"Tammy filed a dissolution of marriage, because in her eyes this was a marriage. Both she and Melissa gave it the dignity of a marriage — they had a marital ceremony back in 2001," Knowles said. "If the court system says there was no such thing as a marriage and tells us we have to amend it to a domestic partnership, so be it. It's a symbolic act on Tammy's part, and frankly she thought it would be better for the children if they were recognized as children of a married couple. ... It was not at all Tammy's decision to go down the route to dissolve their marriage."

Check out photos of Tammy and Melissa

Etheridge and Michaels announced their separation in April.

TVGuide.com's e-mails to Knowles and Etheridge's rep were not immediately returned.