Okay, I kind of need an idea of how to make you get anna back without it being completely weird.
basically i need her to join you some time between the luca cave and your first trip to the moon... Originally I planned to make the item giott gives you, an item that calls her back (equipped with the luca key). But that would keep you from having any significant story dialog about her return which would just be odd...
My second idea was to make Golbez bring her back when you meet him at the moon. (you get golbez at the lunar palace instead of fusoya) This might be odd as well, but I might be able to squeeze in a few lines into that event.
a third idea would be for her to be somewhere at the luca cave, but I donno why she would be there unless i made her standing in front of the door with the luca key... but how to put her npc standing there? i dont know...