Hey Bob, welcome to the fun house.
That said, Victoria 4 “IS” a Poser format character, not a Genesis-based character. I haven’t upgraded to DS 4.5, but I had no problem using any of the generation 4 characters in the renders I did in DS 4.0 on my old laptop.
I happen to only use DS 4 for Genesis because I also have DS 3 Advanced installed, and I prefer to keep my Genesis content in a separate Runtime. You should be able to find Victoria 4 (and her morphs) in the Poser Format section of your Content Tab, and I can’t believe that you can’t load and render her in DS 4.5, unless DAZ decided in their infinite wisdom to not support older characters in the latest version of DAZ Studio.
Somehow I suspect that is not the case, because you would then be excluded from using any of the Poser Format prop sets and environments DAZ sells in DS 4.5.