Hi there. If they aren't showing up in the drop-down menu, they probably aren't being considered norns by the game. If they make grendel noises when they talk (if this is C1) then they might count as Geats or Ettins.
In any event, I would recommend you use a GES selector to try to select them. I vaguely remember that the one in Terra Nornia had an injectable COB version but I cannot find it anywhere. You will probably need to feed them the Selector Cherries in order to select them. You should probably also try right-clicking them, which will select them if they're actually supposed to be selectable.
If you want a more permanent solution you should probably link the download you used so I can investigate it more properly. I can make a quick and dirty COB to select them but I would of course need the norns in my world in order to test if it works.
Thank you for your advice! I think I will try the selector cherries and I think you're right because they are definitely making grendel noises. Thanks a million!