Tree view control in winform vb.net

Question

Hi every one,

 

I am working winform project

 

There is requirment  intially i need to load all parent node and  if user click on that + symobl according that i need to load  data from other table on  basic clicked parent id

 

 

But if load all parent intially so there would wont get + symobl 

 

so how can i do that i am little bit confused

 

 

please assit me