The Difficult Sponsor

Agreed with Kiron, we are professional and we have to do our job in a professional way, however once line is crossed the matter can be escalated and matching response can be generated

Sponsors are allowed to do this. You just need to detail the risks, assumptions, changing baselines etc that are a result of scope additions.

The project sponsor is usually a senior or a very senior employee from an organization that has ultimate decision power over the projects he/she has started.

I don't want to offend anyone but I find it a non-sense for a much junior employee such a project manager to question the decisions taken by a much more senior employee (the project sponsor). Not to mention that the PM effectively works for the sponsor even if there may be no direct line management subordination.

It is not the job of the PM to evaluate how good or poor the sponsor's decisions are but more importantly how can we know for sure that the PM is right and the sponsor is wrong?

Not to mention that the sponsor may have other priorities for which he needs founding so he may consider some projects to be less important than others or than other non-project activities. If needed the sponsor should be able to cut founding to a project in order to allocate the founds to other more important activity.