How we can add and update both in nested array object in MongoDB C#

Question

Here is the MongoDB document that I want to update the serviceName first then add or update both for nested object of vehicle at the same time. Anyone can help to achieve this in C#?

{
    "serviceName": "Service1",
    "intervalKm": 3219,
    "dueSoonKm": 161,    
    "vehicle": [
        {
            "vehicleId": "9100ffff-48a9-ca63-e418-22ca712b0000",
            "dueAtKm": 3228,
            "untilDueKm": 3219            
        },
        {
            "vehicleId": "9100ffff-48a9-ca63-e430-22ca712b0000",
            "dueAtKm": 3219,
            "untilDueKm": 3219
        }
    ]
}

Add and Update both in nested object of MongoDB

Below is my code and it's working for main object but not for nested object. Var result = _mongoCollection.UpdateOneAsync( Builders<ServiceModel>.Filter.Eq(p => p.ServiceId, serviceId), Builders<ServiceModel>.Update .Set(rec => rec.ServiceName, request.ServiceName) .Set(rec => rec.IntervalKm, request.IntervalKm) .Set(rec => rec.DueSoonKm, request.DueSoonKm) .ConfigureAwait(false);

Now I want to update and add object in nested array of vehicle? so, my question how we can add new item in nested array and update if already available? I hope my question is clear now.