A combined pdf outside of SB cannot be saved in SB without first saving it outside of SB. 

You can choose the Print to Smokeball PDF option instead of saving locally first when attempting to get an outside PDF into the documents section of a matter in Smokeball. Here is a link to the knowledge-base support article on how to use the Print to Smokeball PDF option to avoid having to save locally: Save documents, webpages or images to a matter using Print to Smokeball PDF. 

That does not work for me with a multiple-combined pdf; it always errors out and I am forced to save locally before saving by way of Print to Smokeball. Do you think this is an app install error resulting in this repeated error?

Can you share the error message?  Is it from Smokeball or Adobe?

You can also use the Create a PDF or Combine Multiple Files into a PDF feature in Smokeball to combine PDFs in Smokeball.  

I would encourage you to also set up a Q & A session with a trainer.  Work with your Onboarding Specialist ​@Trey Scott to set this up.