General ⇒ Subappendix Title Alignment

[mfiligree]

I need some help with subappendix titles, please. You folks helped me with using subappendices in my chapter document; my problem is that these portions have very long titles. If they go beyond the first line, it would look much better if they are flush against the left margin, instead of centered. Is there a good way to accomplish this? I am using book class, and I've attached a mwe of the file.

Thank you for your help!
Linda