Complex sentence: Durham began work at Henningson Engineering Company for Margre Henningson's father, H.H., in 1940 within ten years became the company officially changed it's name to Henningson, Durham, and Richardson, Inc or HDR, Inc, under Durham's leadership.
Split into simpler sentences: Durham began work at Henningson Engineering Company for Margre Henningson's father, H.H., in 1940. Within ten years the company officially changed it's name to Henningson, Durham, and Richardson, Inc or HDR, Inc, under Durham's leadership.