On Amanda, I think her skin is too tanned. Unless you are changing her personality/character type, she is a shy nerdy girl. And to me, shy nerdy girls don't go outside much to get tanned
Also, if you're going to upgrade the models, I think G8.1 would be a better choice. G9 just came out, so it doesn't have many assets yet.
I assume Roman already gave you converters, but there are plenty of them available here and on the Daz store.
https://f95zone.to/sam/latest_alpha/#/cat=assets/page=1/search=converter