Welding on roof skin

[jac70ss]

I have searched and cannot find what i am looking for. My latest project has some damage on the left rear corner of the roof. I have sourced a donor roof. I am debating whether to remove the entire skin and replace or just "piece in" at the area of damage. The donor skin has some light pitting from surface rust while the damaged roof is in good shape. My concern is warping the roof when stitching in the panel. There is a post of a guy who did a lot of work on the roof of a suburban but i can't find it. Any experiences welding in part of roof skin?