Not sure what tyou are looking for here. There are already subheadings for the County, a regional ambulance service then the cities. Phoenix is listed alphabetically, I would not object to moving it up in the order, right behind the County.
Right, but there’s a “Las Vegas, City of” subheading. We could use that to our advantage to describe the regional dispatch center, as IMHO, it’s a little bit vague and I myself had to do a bit of Googling.
Ok, Las Vegas should fall between Henderson and Mesquite in alphabetical order, but they're listed separately.
By regional dispatch center, I assume you mean the Phoenix FD Regional Dispatch Center? There are two main regional fire dispatch centers: Phoenix FD and Mesa FD. Phoenix is on the RWC, and also has 15 VHF-High channels. Mesa is on the TOPAZ RWC, and also has a handful of VHF-High channels. I suppose it could be argued that Rural-Metro is the third, since they directly serve communities all around the Valley, as well as provide dispatch services for other departments/districts, such as Circle City-Morristown in the far Northwest Valley, as well as others in Yavapai County.
I will throw out on opinion. The trunked system of the federal Bureau of Reclamation system is properly listed in the "All Trunked Systems in Clark County." However, when I look up the federal government pages on the Nevada, California and Arizona state pages, using the federal government link, this trunked system is not listed on the Bureau of Reclamation listings. I would not normally look for this federal agency on the bottom of a county page. I would look it up on each federal listing at the top of the state DB pages.
The L.A. County page has everything that is major at the top of the page, right below the county listings, They are L.A. City and Long Beach in their own headings and out of order with the rest of the cities that are listed under the "Cities" heading below. Is that what the OP is talking of doing? I'm not sure if the LA Co page being set up that way is helpful or not. LA City and Long Beach have 44% of the county's population so maybe that's why it's that way.