Step 2 - Part B - How am I going to do these alterations?

What I need to do is make a pattern from my "pattern shirt".

I'll turn the modified princess seam into a true princess seam, and then do a full-bust adjustment to that.

I will start by cutting along the seams (not taking them out) and removing the entire front panel of the shirt.

It looks like this:

You can see that I've used a marker to draw a solid line where the actual seams are, and a dotted line where I am cutting to make true princess seams from the modified princess seams which are already there.

Here are the pieces after they've been cut apart:

I traced these, and created a paper pattern.  I then performed a full bust adjustment on that pattern.

I'm not going to actually document the bust adjustment process.  Other people have done that better than I could, in fact, here's a link to the site I used:  How to Make a FBA (Full Bust Adjustment) on Princess Seams.

Here are the finished patterns: