For the purposes of this subpart, a child is considered to be:
    
    
        
        (a) 
         A biological child who lives with the Federal employee;
     
    
    
    
    
        
        (e) 
         A child for whom a judicial determination of support has been obtained; or
     
    
        
        (f) 
         A child to whose support the Federal employee, who is a parent or legal guardian, makes regular and substantial contributions.