AutoCad :: Copying Viewport With Aerial?

I am working on an alignment sheet for a gas line. I am showing an aerial in my main viewport in plan view. I am only showing line work between match lines nothing pass that except the aerial. However I have two more viewports aside from the main one. I have one to each of the sides of the main viewport to show the aerial image only pass the match lines. My viewports are locked all three of them, yet my image on the viewports to each of the sides of the match lines keep acting up and won't show correctly every time I zoom out or in. They'll be a time that they will but if I zoom out or in after that they will move and not match my main viewport were the line work is at. I only copied the main viewport and resized it to fit in the template pass the match lines. Created a reference point to zoom into my aerial after the match line and it all works until I'm ready to plot and zoom out then it messes up.