As people change their minds, preferences, trends over time so does the businesses and markets also change accordingly. Therefore requirements are inherent to change in any project.
As a BA you will have to do few rituals when ever change requests sits on your desk.
So the first thing BA will do is to document the change request so that it can be used as an artifact for audits and future references. Then BA will analyse this change request to access is it really a change or an enhancement or a defect discovered from the previous need communication. And yes, In order to move forward BA needs approval from the project manager or from the change control board.
Feasibility Study is conducted on the change requests to access the complexity of the it because as the complexity increases the scope of the project also increases as will as the delivery time. Along with the feasibility study impact analysis is also conducted to measure change to project. Finally effort estimation in terms of cost and time to implement the change in the project.
When the analysis is finished and change request is approved by the change control board or the project manager BA will have to communicate the same with respected stakeholders to understand the impact of the change on the organization and to minimize negative impact that results from that particular change.
Effective change management demands consensus among stakeholders to avoid conflicts. BA must lead the stakeholders by showing strong personal commitment and contribution to the project.