I need an advice , Please suggest how to achieve my goal,

Example:  I have a REQUESTER and Technician A,  Technician B and Technician C,

1. Requester Fills Template  A

2.  Technician A  has = Template A Which contains  some fields  That all technicians can see

3. Technician B  has = Some additional Fields to fill that Technician B and C are able to see but not A

4. Technician C has = Some additional Fields to fill that Technician C is able to see but not A and B

I want to make a Template that will be filled slowly  TECH A starts TECH B continues to fill and TECH C  prefills and resolves,

i Tried to  make Field & Form Rules by conditions , it works on form load  if you edit request, but if you just VIEW request all fields are VISIBLE even if they are set to hidden ,

I tried Business Rules  IF  Group is A assign to TECH A and Change incident template to TECH A 

but business rules does not seem to work with changing incident template, 

i tried making separate incident templates for all,  i deleted all fields from default template,

and created TECH A , B  and C templates, but  in some cases TECH A can see TECH C s fields EVEN IF DEFAULT TEMPLATE is choosen where all fields are deleted,  how is that possible?

I am stuck Please help. how would u achieve that goal i have?