A bit about me: I am a registered commercial architect licensed in NY and VA, as is my wife.

If you have the funds but not the experience, for your first project team up with a developer that knows the approvals processes and how to find a good property and connect with tenants and that has good team members- brokers, architects, engineers, environmental inspectors,  attorneys, etc. and knows the ropes.

you would have thought the architect would have found a way to add another bathroom to this mansion

So I'm not sure, I would check with your architect and zoning attorney to see what's allowed by right.

Used my knowledge as a licensed architect to optimize value add for better profit.

I had local architects doing a walkthrough for $150 to see if it's even feasible.

If so You need to hire a design build contractor or an architect to develop plans and specifications to start moving forward with the project and permitting process.

Hi Eric,Look for a local "Architect". 

I need an in-house project manager with a design/ architect degree.

This way you creat it once and sell it to many.As a GC I had in house design coordinator.For flips I put this together myself and I send it out to all my contractors.Asa developer I hire designers for the projects unless the architect has that in house and I like their style.Hope this helps