Add a drop down menu and debugging with CakePHP

We have created a registration form to validate and complement the information on centers present in our data base. Your mission 1- Correct the following bugs: Bug 1: Step 1 of the form Changing the status of the center (radio button) must change the "id_siège" field in the database. If the center is M, the field "id_siège" take the value of the id of the center. Bug 2: Step 3 and 4 of the form If in step 1 the center's status is A and is modified at that step, the information entered in step 3 are no longer stored in the database. This also has implications for the validation of step 4. Bug 3: Step 3 of the form The city field displays the city corresponding to the center while the city should display the corresponding to the "siege" (the head office). 2. Add a drop down menu + display the corresponding information (ajax). This drop down menu allows the user to choose the head office among all centers with the same name, listed in our database or create a new one. The information on the head office (address, city ...) will be displayed in the corresponding fields. If the head office is already identified in our database, it will appear by default. The addition of this drop-down menu should avoid duplicates in the database. It will be linked to the field already in the form