@maryssmith, As I think, the problem is not "the genital prop", but the "model" to which you apply it... Daz has the "bad habit" of applying morphs like JMC's, etc..., and that hinders the work of "apply" to a "character", even if it is based on the "base genesis 8 Female"... If it is applied to , for example to "Babina 8, or Alenxandra 8", the topology is different..., so that the position coordinates differ "a few tenths of inches/millimeters...", but it affects the whole....
I think the best thing would be to make a specific morph for your model... (Either with "DSF Tools" or with an .obj export, and modify it in Z-brush, or Rhino... -Sorry: Blender is called very bad with Diaz..)