The other day, we were actually talking about this item.
Fit Control for Genesis 3 Female(s)
https://www.daz3d.com/fit-control-for-genesis-3-female-s
Using it is fairly easy. After you have fitted your cloth on your G3 character, select your character and click on the "activation script" button in the fit control folder in Daz studio. In a few seconds, it will create into each clothing worn by the character all those morph listed in the product.
All what is left for you to do after, is to go into the clothing you desire (i.e: the panty) and start toying with the dial preset you like.
For example, there is 5 morphs concerning the crotch with 2 that allow you to do what you seem to be looking for. (expose the crotch to the left or right)
I suggest you give it a try. It's also very usefull for a lot of other things. I'm almost always using one of those morph in every cloth i fit on my characters to fix some knick-knack here and there.