Supergirl/WMG

Pre-Crisis Supergirl was erased from history, but her spirit lives on in the Post-Crisis Earth
In [Christmas with the Super-Heroes 88], Deadman met a female spirit who called herself Kara. [In an issue of her solo book in the 90's], Linda Danvers met a glowing being named Kara. And Post-Crisis Batgirl [had an imaginary friend whom she called "Supergirl"].

After her death, Kara roamed around New Earth universe, trying to help her alternate universe's family and protecting Linda Danvers and her Post-Crisis alternate self. She knows the universe was altered because of Flashpoint and Dr. Manhattan's intervention, but she is unable to warn her family or the remainder heroes.

After the "Convergence" Crisis Crossover, Earth-1 Supergirl returned to her own universe
"Superman: Lois And Clark" revealed that Pre-Crisis Supergirl left after surviving the Crisis. Kara obviously returned to her Earth and her cousin.