I am filing a SAR and don't have enough room to put everything in the narrative. Do we put the rest on a regular sheet of paper or use a blank SAR to file the rest. I was going to do the latter and attach it.

The instructions state: "If necessary, continue the
narrative on a duplicate of this page."

So I'm not sure if you paper file? - but you just keep repeating Part 5 until you get it all in there.

I ditto (not as)newbsa.
I try to leave out not-so critical information, but in a couple of instances i've used an extra narrative page.