Complex sentence: He had another son, Ben, who had been killed in a fight with the local Doctors son Luke Mcallister, although he was found to have a heart defect, this did not stop the Dingles pointing the finger at Luke.
Split into simpler sentences: He had another son, Ben, who was killed in a fight with the local doctor's son, Luke Mcallister. He was later found to have a heart defect but this did not stop the Dingles pointing the finger at Luke.