Hmm, clarification :
- You want to send Case ID to custom object via custom button? Yes? No?
- You want to REMOVE "New" button from related lists under Case detail page? Yes? No?
- You want users to complete/finish previous "section" before going to next section? Yes? No?
Please provide as much info as possible!!
Possible solutions :
- Use a Visualforce page to get the "on click" functionality.
- Make a special field on the custom objects. Perhaps a checkbox.
- Use different page layouts + record types to show/hide new button.
- Use Workflow rules to change record types depending on what conditions you want.
- Visualforce page is also very useful for step-by-step or section based work. You CAN use a VF page to do your section by section completion.
You may refer to this answer for more information :
Link 1. How to pass parameters to VF page and how to update fields via controller
You need to make a detail page button on the object and either pass the ID via (remember to replace Case_or_YOUROBJECTNAMEHERE with your object and YOUR_VF_PAGE_NAME by your VF page name) :
You need to EDIT the Page Layout. Go to "Buttons" sub-section and remove (drag n drop the required button to the upper holding area or press the small "(x)" next to it) the desired button.
Refer to THIS EXCELLENT GUIDE. Basically, you're moving through 4 VF pages, each with their own functionality, using
PageReferences to move to each of them.
Hope it helps!! And I hope its not too late :)