It appears renaming a TS project file acceptable from the IDE but NOT acceptable when the named is changed from file explorer. There is no method to relink the tsproj.tpj with the source sequence files.
I only method I see is to start by renaming your original tsproj file using file explorer, from the IDE delete the original TSProj file. Create a new tsproj file, adding your project members. If I rename a TSProj file in the IDE it should rename the file, looking from file explorer.