Yes, you are able to select a new holding (including generic) and create an ex-post review.
When the ex-post review loads, you will see the same screen as when using a converted holding from ex-ante research, but there will be no Previous state.
As seen below:
For more information on how to create an ex-post review, see articles:
Video - Ex-Post Reviews.
Article - Ex-Post Reviews - How to create a review
