To create a dummy FRF block with automation, is not that simple and straight forward. For getting the function class and a lot of required properties correct is not easy.
Maybe this work-arround can help you.
You can get a FRF block in 2 simple ways:
Save this FRF block in a dummy LMS project, when needed you can get it from this project.
Use the DataBrowser to get it, so that you don't have to open a second LMS project.
Like I said not the best, but a solution.