I do not know of any instances were LW medical units were attached to Heer formations as a primary medical support component.
Before the war, most folks who were in the military at age 40 were career military with many years under their belt. I do not think that there were any new recruits of that age who were accept into the military. During the build up, I feel that they were accepted under limited circumstances, if they met the physical requirements. Most folks of this age were accepted as Officials, if they had needed specialty training.
Is there anything more you can tell us about him? Do you know his LW rank? Do you know about any of his awards?