I will suggest a bapkplate/wing combo for her, but since this is probably a new piece of equipment which you have little or no knowledge of I will explain a bit more.
A backplate/wing or BP/W has several key advantages for women and men:
-using a hogarthian concept to set up your system means you will never need to by a new setup as she grows. you will need to buy about $20 in webbing every couple years though depending on how she grows and how much use the system gets.
-a BP/W allows the diver to dive any tank configuration available including single tanks, use pony bottles, double tanks, sidemount tanks, stage bottles, etc. I have carried as many as 9 tanks on 1 dive using a plate.
-a BP/W is not gender specific for fit, especially using a hogarthian 1 piece harness. there is no need for a chest strap (which tend to be uncomfortable for women).
-a BP/W is usually much easier to dive, it allows the diver to achieve better trim which reduces drag and increases air consumption.
-you can use the same setup as you grow or transition through diving. if you decide you want to become a cave diver or wreck diver you wont need to change setups.
-BP/W's stand up to abuse better than traditional bcd's and are almost maintenance free.
-Diving Hogarthian means a "clean" system which lacks clutter or extra gear that can produce additional drag or confuse the diver.
-the hogarthian bp/w is used by divers world wide including 99% of record holders like the WKPP of florida who used the system to travers 18,000 feet into a cave at an average depth of 300 feet deep.
-bp/w's are becoming more and more popular and are now produced by about a dozen companies.
-bp/w's usually cost about the same or less than jacket bc's depending of course on brands but you will never need to by another plate, a bc may only fit your daughter for a couple years.
-you will need less weight to sink, thus smaller weight belts or maybe even no weight at all depending on what plate you get.
-a bp/w facilitates the mounting of any accessories such as light canisters, pony bottles, drysuit inflation bottles, lift bags, marker buoys, knives, reels/spools, additional weight, underwater tools like hammers, etc.
-if pockets are desired, a full array of pocket designs are available that can be tailored to your specific needs.
-bp/w's hold their value about 3 times better than a bcd.
-and of course there is the cool factor or having better buoyancy and trim than the jacket divers and the modularity of being able to dive any conditions at any time and in any place in the world.
If you decide this is a good option, you might not be able to dive locally so buying online could be a better option. it will be cheaper to buy online and will offer you a much better selection.
if your going to get a bp/w you will likely have to buy the components separately and assembly it yourself (takes an hour or so the first time you do it). you will need these items at a minimum:
-1 backplate in either stainless, aluminum, or kydex.
-1 single tank adapter, its kinda considered optional but makes diving a single tank much more comfortable.
-1 wing, if diving single tanks you wont need anything more than a standard 32lb wing. smaller is better usually to remain steamlined. more on this later.
-20 feet or so of 2 inch webbing. with the availability of sewn crotch straps I kinda like going that route but you will have plenty of webbing to make your own. You DO want a crotch strap!
-3 of the 2 inch d-rings, though depending on preference you will see people with more and if you make your own crotch strap you will need 2 more also for a total of 5. I have 8 which includes the crotch strap ones.
-belt slides for each D-ring plus 3 belt slides.
-some 1/8 inch bungee cord or bicycle inner tubing.
total cost should be between $300-700 depending on brand, new or used. mine (SS version) was made with all new components for about $475.
thats it, no padding or pockets. these can be added as necessary. usually I hear after the first couple dives people want pads but adjust to not having them after a couple more. they are not needed but depending on the person you may desire to add them.
there is an array of companies to investigate like these:
Deep Sea Supply
Ocean Management systems
Dive Rite
Halcyon
Zeagle
Hammerhead
Oxycheq
Solus
FredT
Hollis
Highly Optimized Gear (HOG brand)
etc.
all of them produce at least stainless and aluminum plates and all of them accept FredT and Hammerhead produce a selection wings. All wings and plates use a standard 11" bolt pattern so dont worry about compatibility.
For webbing, d-rings, stainless snaps, bungee, and other accessories check out:
Scuba equipment, Dive gear, reefscuba.com, Manufacturer of scuba diving equipment. Buy brass hardware, stainless steel hardware, surgical tubing, latex surgical tubing, bungee cord, parachute cord, Waterborne watch bands, SEACURE mouthpieces, velcro
Dive Rite Express
Custom Straps, Nylon & Polypro Webbings, Metal & Plastic Buckles at Strapworks.com
Nix dog collars (google them) for stainless snaps.
or others. google is your friend.
if you are in dire need of pink gear, if she is into that kinda thing, you can get all that stuff in pink and there is a thread going now which discusses various locations to find pink stuff.
I am not a DIR diver, though DIR websites seem to be the best places to find good information on Hogarthian equipment configurations. Hogarthian is a term named after Bill Hogarth Main who started this approach to diving several decades ago. There is nothing wrong with adopting the DIR philosophy though if its something that interests you, I would say many of the best divers (speaking on technique and knowledge about diving) tend to be well routed in the DIR or GUE fundamentals.
here are some links to find more info on Hogarthian diving and assembling backplates:
Hogarthian Harness BC System
YouTube - Threading a Backplate System
The Hogarthian Gear Configuration
Hogarthian Divers - DIR diving - Doing It Right - Diver - Recerational and Technical Diving
Equipment Configuration | Global Underwater Explorers
DIR-diver.com - Adjust the backplate
that should be enough to get you started anyway, let me know if you need any more help. T