Complex sentence: While Nancy's drug activities increase, Celia wins Doug's spot on the town council, due to the incompetence of husband Dean (a lawyer), who forgets to file Doug's paperwork, so leaving him off the ballot.
Split into simpler sentences: While Nancy's drug activities increase, Celia runs for, and wins, Doug's spot on the town council. Her victory is due to the incompetence of her husband Dean (a lawyer), who forgot to file Doug's paperwork, leaving him off the ballot.