Select the files you want to find drafts for then Tools > Assistants > Where Used.
On the form that appears you can select the locations to search and whether to include/exclude sub-folders.
The Process Options button will let you restrict the file types to search for.
The new design manager makes that process much much easier. You can now start with a draft, get the assembly and parts, then also add any other draft files associated with the assembly or any parts.
I never could get that working with the old revision manager where you copied a collection of related files including multiple drafts.