If your rabbits are experiencing congestion, coughing, sneezing, and sounds of mucus in their airways, it could indicate an upper respiratory infection or another respiratory issue. Here are a few suggestions:

1. Veterinary Care: It's important to consult a veterinarian who specializes in rabbits or exotic animals. They can examine your rabbits and provide a proper diagnosis and treatment plan.

2. Isolation: If you have multiple rabbits, consider isolating the affected rabbits from the healthy ones to prevent the spread of any potential infection.

3. Clean Environment: Ensure that the rabbits' living area is clean and well-ventilated. Remove any potential irritants, such as dust or strong odors, from their environment.

4. Humidity: Increasing humidity in the rabbits' environment may help relieve congestion. You can use a humidifier or place a damp towel near their enclosure.

5. Steam Therapy: Steam therapy can be beneficial for respiratory congestion. You can create a steamy environment by running a hot shower and placing the rabbits in a safe, well-ventilated area nearby. Ensure that the rabbits are not directly exposed to hot water or steam.

6. Hydration: Make sure your rabbits have access to fresh water at all times. Maintaining proper hydration can help thin mucus and make it easier for them to clear their airways.