update parent table only EF4.1

See more:

C#5.0

EF4.0

entity-framework

i have this method to update 2 tables (parent and child) :

public override void Update(ArCollectiveBilling entity)
        {
            var existingEntity = (from e in Entities.Include("ArCollectiveBillingLines")
                                where e.CollectiveBillingId == entity.CollectiveBillingId
                                select e).FirstOrDefault();

            // Cannot Update if Entity Doesn't exists in database
            if (existingEntity == null)
                throw (new InvalidOperationException("Entity Doesnt exist in database"));

            if (existingEntity.Vers != entity.Vers)
                throw (new OptimisticConcurrencyException("Another user has updated the database"));

            // Update entity Vers and Audit Data field
            entity.LastModDateTime = DateTime.Now;
            entity.CreateDateTime = existingEntity.CreateDateTime;
            entity.CreateUser = existingEntity.CreateUser;
            entity.Vers = existingEntity.Vers + 1;

            // Update Standard Code Type
            existingEntity.Merge(entity);            
            Entities.ApplyCurrentValues(existingEntity);
        }

code above makes EF 4.1 send query to update parent table
and insert 300 items child after delete it all

is this behavior of Entity Framework?

could i update parent table (Entities) only without send query to delete and insert 300 items on child (ArCollectiveBillingLines) table?