I have the Quest interface and have no problem saving my comments to the lab. I pull up the lab to sign off. Then I click the Orders button. Under "orders" I select the "Other" tab and then type as much as I want. I send the orders to nursing who adds their comments regarding contact with the patient. The entire thing is saved. When I go back later to pull up the lab, the comments are still connected. I do the same when I sign off the labs that are imported from paper.
If I want to compare the labs to the rest of the chart, I first open the patient's imported before opening the labs so I can have full access to the record and open the labs.