could superwoman's earth-1 be the same one linda danver's had a child in?
No, because Linda Danvers replaced Kara Zor-El as Supergirl in "Many Happy Returns". But Linda Lee Danvers (aka Kara Zor-El aka Supergirl) appeared in the first Kristen Wells Superwoman story.
And if you accept "Whatever Happened to the Man of Tomorrow" as canon in regards to Superwoman, not only does Kara Zor-El's memorial statue appear in the Fortress of Solitude, but a young Kara with the Legion of Super-Heroes actually visits Superman!