>>34623365She's not, the person that designed her said he created her from scratch and that she's meant to be a different character.
http://outdoor.geocities.jp/twnfh640/pokemon2.ds.htmlOn top of that Kris was going to be in HGSS originally since she still has a pokegear sprite in the game meaning the decision to include lyra instead of her was made late in development. You can find it on her bulbapedia page.