FOs and direct & indirect fire support in question

[burroughs]

Let's say that I happen to have within my force an HQ element, it could be a company or battalion command element and sometimes even a qualified FO who have a radio set; the question is whether that facilitates my both on-map and off map fire suport if they have a clear LOS to the target and can spot? Or there is no difference when compared to that situation in which a - be it - mortar crew can see the target and lay some direct fire on that?