You can absolutely comment on a lab request you, or another user has made. In the patient’s lab activity stream, you’ll notice an arrow icon in the lower right hand corner when you hover over the particular lab in question.
Clicking that will bring up a correspondence box where you can enter your notes on the lab.
You can edit your note by clicking the pencil icon, which is also visible when hovering over your note.
The note you submit will be visible to all Atlas app users from that point on, assuming you don’t delete it. Only you can delete/edit the note – other users don’t have the authority to do so. It will not be visible to the Lab provider nor the patient.