I need to break an OB rule. When and how to do it?

The Phase 2 preparation for SM has several rules that only exceptionally can be broken. Here you can find more details about the OB rule and policies.

While the Phase 2 rules can never be broken unless in really exceptional cases, the general OB and container rules might, if this is necessary for achieving your scientific goal. You can find a complete list of rules and recommendations here.

Breaking one of these rules requires in any case asking a permission to ESO. This is done by sending a waiver request or a Program change request through p2. This request must be sent to ESO well before the deadline for the submission of your Phase 2 material  in case the request needs to be discussed by the user support astronomer and the Chilean science operation team. 

You can have a look here for more detailed info and at the following tutorial for a quick guide:

How to submit a waiver request in p2

How to submit a target change request in p2

How to submit an Instrument change setup in p2