Here's what I'm trying to do. I want the Name, the Title, and the length of the red Title box all to be editable in Premiere.
I'm working with a videographer who does his editing in Premiere. In the past he would create static lower third graphics in Photoshop, import it into Premiere, and then just fade them in and out as needed, and each time he had a name/title change he had to go back into Photoshop. My plan was to provide him a single .mogrt file that he could import in then change the name/title all within Premiere. However, if the first name is in regular on one layer and the last name is in bold on another layer, what happens when you have different length first and last names? I need the last name to adjust with the first name. Putting them on separate lines won't work, as far as I can see.

Looks like you'll require three text layers - one for FIRST, another for LAST and another for TITLE. And Rick's right in that you'll need to offset LAST from the right edge of FIRST and you'll want to use sourceRectAtTime.
The solution is to offset the LAST layer from the right edge of the FIRST layer.
Paste this Expression into the Transform>Position of the LAST layer -
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// declare target layer
t = thisComp.layer("First Name");
// declare the offset value in pixels
offsetXpos = 50;
// declare sourceRect
tRect = t.sourceRectAtTime();
// get location of right edge of target layer
tBR = t.toComp([tRect.left+tRect.width,tRect.top+tRect.height]);
// apply offset to xPosition of target layer and set yPosition to equal that of the target layer
[tBR[0] + offsetXpos,t.position[1]]
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