Complex sentence: They realize that George and Lillian had an illegitimate child and if he's still alive he'll inherit the fortune then find a diagnostic medical record paper from Martin's doctor in Switzerland and discover that Martin has a hereditary disease for which he is terminal.
Split into simpler sentences: They realize that George and Lillian had an illegitimate child and if he's still alive he'll inherit the fortune. They find a diagnostic medical record paper from Martin's doctor in Switzerland and discover that Martin has a hereditary disease for which he is terminal.