How do you add custom document types in the (dita) resource manager?

Hi Alexia, sorry for the tardiness. 

so in my custom folder, which aptcustom points to. It is on an external drive shared by my colleagues, so I can't rely on a local solution.

custom_init.acl

############################################################################
#
# Add within this function to customize the menu on startup
#
# 	
function load_menu(){

	menu_add -before .File.#15 "Publish PDF and Release Print License" -cmd {
		compose_pdf();
		license_release("PrintPublishing");
	}; 
	
	menu_add -before .View.#7 "view_code" -cmd {
		edit -current -untagged;
	};
	
	menu_add -before .View.#8 "view_normal" -cmd {
		edit -current;
	};
	
}

add_hook("menuloadhook", "load_menu");
#
###

##############################################################################
##############################################################################
# Adding custom options for when you create a new file
# remove an item by using ^ in front of the field. ex. ^techinfo;
#
set newlist=" \
	techinfo; \
	techinfo-rdedit; \
	techinfomap; \
	dita\\bookmap; \
	dita\\map; \
	dita\\ditabase; \
	dita\\keybase; \
	dita\\ditaval; \
	^dita\\learningBookmap; \
	^dita\\learningMap; \
	^dita\\learningGroupMap; \
	^dita\\learningObjectMap; \
	^dita\\learningDitabase; \
	dita\\DMPmap; \
	axdocbook; \
	asdocbook; \
	html; \
	xhtml; \
	html5; \
	xhtml5; \
	^freeform;^ASCII|Text; \
	T:\\DTD\\ApplicationNote\\ApplicationNote.dtd; \
	T:\\DTD\\DataSheet\\DataSheet.dtd; \
	T:\\DTD\\Errata\\Errata.dtd; \
	T:\\DTD\\ModuleSpecification\\ModuleSpecification.dtd; \
	T:\\DTD\\NewTechnicalReferenceManual\\NewTechnicalReferenceManual.dtd; \
	T:\\DTD\\UserGuide\\UserGuide.dtd; \
	T:\\DTD\\ReleaseNote_2\\ReleaseNote.dtd; \
	T:\\DTD\\FreeDocument\\FreeDocument.dtd; \
	"
#
###

So as you will notice at the bottom, I have links to some custom dtd (docbook derivative) files. It is not included here, but I also created some dtd's based off of dita. There are a few elements and filters and such that I added to these dtd's. So I believe with this, it is possible to see the new doctype in the new document window, and this is fine. 

But now I want to work with dita and dita maps. I largely prefer if the team uses the resource manager to create and insert new topics. 
I have these new dita dtds in a separate folder, outside of the custom/doctypes/ folder.  

However the documents listed only provide me with the out of the box dita documents, and I need to ensure they're shown the new ones instead. But I am struggling to find where I can update this list. For reference, I found the Resource Manager tab customization information on the website, but not the list within (specifically the how-to, or at least even a sample).