I've come to understand the necessity for stakeholder involvement throughout the Requirements Gathering process. But what if it's another BA who is the stakeholder company's point of contact whom you'll be gathering requirements from instead of the stake holder themselves? Is there an advantage? How do we leverage the strength of our Requirements  Engineering knowledge to come up with an appropriate set of requirements for a project?

I've been assigned to my first stint at Business Analysis, doing requirements gathering on a Financial Services company's IT upgrade project.  Currently, the interfacing is mainly between myself and their BA. A lot has been said of gathering requirements from stakeholders, but this BA (we'll call her J) is my point contact and perhaps the one I've been assigned to doing most of my discussions with. What's the best way to gather requirements through another BA? I've heard it said that it is possibly more advantageous to liaison between BAs since we all speak a similar language of Requirements Engineering. But does this replace the need for stakeholder involvement?

Practically, what are the best questions to ask the stakeholder company's liason BA in the spirit of gathering requirements?

Currently, my documentation growing with Process Flow Diagrams, which are showing to be very effective in communicating requirements to J. My plan is to direct these diagrams as well to the actual users of the system to see if the proposed system will be correct in their perspective.

Yet perhaps with me being very green at the job and learning as I go along, it's important to ellicit deeply to find as much information and requirements as I can with the given amount of time. Are there best practices for interactions between BAs, one who is taking requirements, the other which is communicating requirements. Perhaps this is all too simple a concept, and I'm clearly missing out on something, but it could also be an issue that another BA has experienced. Do share your thoughts on this current issue I have as I trudge along to gather whatever I can on the issue.