As long as you have those and EOBs, you are golden. If not, they will deny payment. I lost an EOB and had to contact BCBS. They faxed me it and the FSA provider couldn't read it. Had it mailed from BCBS and submitted this new copy to FSA provider.
A ton of silly work and all my fault!
Now, BCBS and SO's health care provider have EOBs online, so it's easy to download for verification.
You'll love the CC option.