Add onion, green pepper, celery, garlic, sausage, and chicken. Stir to combine.
Cover crock pot and cook on LOW 4 to 5 hours.
Set a larger strainer/sieve over a large bowl and pour about 75% of liquid in the crock pot through strainer. You should have about 3 cups to cook the rice in. Add water to get 3 cups if necessary.
Return all solids to crock pot. Stir in parsley and shrimp. Cover crock pot and cook on LOW 30 minutes.
Meanwhile, bring the 3 cups of liquid to a boil. Stir in rice and cook according to package directions.
Add cooked rice to slow cooker and mix in. Serve.
Video
Notes
I tried to keep the ingredient list fairly reasonable. For extra flavor, try adding 1/2 teaspoon of dried thyme and/or 1/2 teaspoon white pepper.