I've got two saves, one with Miranda and one with Ashley kept. I've also got a save just before the final section, where I can go up to which ever of the 3 girls I want and then tell them I want them. So theoretically I could easily get a save with Jack and Tali, too, without much trouble.
If I wasn't so god damn lazy, I would have replayed ME and romanced liara instead. How was I meant to know she was going to turn into such a badass? The only reason I romanced Ashley was for the achievement(Yes, I'm an achievement whore, hush).