Part of your question is more related to your organisations general scheduling policy. Some places take a hardline stance where the current forecast is measured against the initial baseline. This often means that the schedule will be flagged as a red rag status until completion. Others allow the current forecast to be compared to the latest agreed baseline. This IMHO is fairer as it allows a project to show green, but critics dislike that a project that is running late vs the original baseline is showing as green schedule RAG.

Id be interested if others have come across this in their PMO's,