I may have missing aunts/uncles but I have no idea how to find out who they are
I don't really know if this is the best place to post this, but there has been stories about my maternal grandfather getting a girlfriend pregnant, and another story of my maternal grandmother getting pregnant and I am trying to see if I can find who these people are.
So the story about my grandfather is that he had a girlfriend in highschool. She ended up getting pregnant, but didn't want to raise the baby. Supposedly her sister was married and wasn't able to have children, so the girlfriend gave custody to her sister. The girlfriend would have likely went to highschool in Lansing, Iowa, and my grandfather went to highschool in Desoto, Wisconsin. The girlfriend's dad was from Genoa, Wisconsin, and I think his name had Leland somewhere in there (maybe with a different spelling, but it would be pronounced lee-land) but I could be wrong. My grandfather lived in Genoa at the time, and the girlfriend might have as well.
The story about my grandmother is that she, while married to my grandfather, got pregnant. For some backstory, they had two children, my mother being the oldest and my aunt being the youngest. My mom and my aunt ended up finding an ultrasound photo from August 8, 1989, exactly one year after my mom was born and well before my aunt was born. My grandmother said that it was my mom and the hospital's machine had the wrong date, but the baby in the ultrasound was not developed enough to be her. My mom wasn't born premature either, so that doesn't make any sense. I've thought about the possibility of her maybe having an abortion or a miscarriage, but I'm not sure. She could have also decided to give it up for adoption if she had it, but no one knows. Currently the ultrasound photo is missing, so we really don't have a lot of leads to this.
My mom has taken a DNA test, but it hasn't shown anything that could point us to who these people are. We can't really get any answers from either of my grandparents, since they will both take these secrets to the grave. My grandma did confirm that my grandfather got the girl pregnant, but did not elaborate. If anyone has any ideas of how to find these people, please let me know. I'm not really sure what to do about all of this.