Transition between roof pitches

I have a 14 year old metal roof on the house I recently purchased. I had a very reputable roofing company come out (I wanted someone with expertise so I went out of my area) and take a look at the roof prior to purchase and knew it needed some maintenance. There were some fasteners which had backed out and I asked the guy if a transition piece was needed between the steep pitch and lesser pitch as there was not one there but I had seen one on other houses. He said it should have been installed but that it would be very difficult to do now. Well the crew came out and added new fasteners and told me that I really needed the transition metal as the back porch already had a leak at this point (thankfully it is outside) and the front porch which is over a hard textured ceiling in the house was beginning to leak. The workmen said they could have installed the transition metal on the existing roof had they would have known it was needed and that it was not a major issue to do so but they did not have the materials. It was a 3 hour round trip to get to my house and it only took an 1-1/2 hours to do the fasteners so they were on the road more than working. My question is can this transition piece be added without removing entire roof panels as the original inspector had indicated? I need it done but now I have an inspector telling me one thing and the installers/workman telling me something else all from the same company.

Entire roof is metal? They will have to unzip the upper the upper panel to install the transition metal but it should be easily doable.