Complex sentence: Guaimar further worked to stabilise his dynasty by altering the pattern of succession: he appointed his son Gisulf I as co-prince in 943 and Gisulf succeeded in 946.
Split into simpler sentences: Guaimar further worked to stabilize his dynasty by altering the pattern of succession. He appointed his son Gisulf I as co-prince in 943, and Gisulf succeeded in 946.