Hello Toddalin
What you are doing is making sure the drivers sum properly through the crossover. I used to do the same thing when I had my RTA. It finally gave up the ghost last year.
An RTA is not the right tool to judge time alignment you could be one or more cycles out of alignment and you won't see it.
Depending on spacing and crossover point's It could be in time alignment but more than likely, like most other speakers it is not.
With Gregs example using the Array to Time align them he would have to move the horn back on full wavelength @ 800 Hz. They sum properly because they are in phase at the crossover point but the woofer arrives behind the horn instead of with it because of the position of the upper horn cabinet.
Rob