Adds the elements of another AppenderCollection to the current AppenderCollection. 
 Adds the elements of another AppenderCollection to the current AppenderCollection. 
public virtual int AddRange(AppenderCollection);
 Adds the elements of a IAppender array to the current AppenderCollection. 
public virtual int AddRange(IAppender[]);
 Adds the elements of a IAppender collection to the current AppenderCollection. 
public virtual int AddRange(ICollection);
AppenderCollection Class | log4net.Appender Namespace