You've gotten some good info. I'm not sure if you want the hand held in place of the fixed wall shower head, or in addition to it. So I'll try to describe both. Part One, you just want the handheld on a sliding bar: If you just want the hand held and don't want the shower head that came with the D500058, then you need the Danze D469058 wall outlet. You'll use a short brass nipple to attach the wall outlet to the copper fitting inside the wall. The same type of copper fitting that a typical shower arm would get threaded on to. The nipples are only $1-$2 at any box store. You can buy several of differing lengths (1-1/2" to 2" generally), use the one that fits, and return the others. The length needed depends on how deep the drop-ear fitting is buried in the wall plus how thick your tile backer board and tile are. Brass nipple: 1/2" Drop-ear fitting: Your copper tubing get soldered into the "smooth" opening, the shower arm of the shower head or your brass nipple for the wall outlet get threaded into the threaded end. Use teflon tape of teflon pipe dope on all threaded joints. When you plumb it, have one port from your supply valve go to the tub spout, the other port that would normally feed the shower head will instead be plumbed to the Danze wall outlet. Screw one end of the handheld hose to the wall outlet. Attach the other end of the hose to the handheld. Mount the wall bar on the wall. Attach the handheld to the wall bar. Part two, you want the handheld in addition to the fixed shower head on the wall: You'll still need the Danze D469058 wall outlet. You'll also need a diverter valve. I took a quick look at Danze's offering and only see a 4-port diverter valve. All you actually need is a 3-port valve, but a 4-port can still work and allows you to stay in the Danze family. The Danze 4-port is actually designed to have one if its ports capped if you don't need all three outlet ports, the cap is even supplied with the valve, so they make it easy. If you want to go with a 3-port diverter, pick anything you like. I'll stick with Danze for the description: You'll need the Danze D130000BT diverter valve and the Danze D560858T Parma trim kit to go with it. The installation instructions that come with the diverter valve are pretty self explanatory. However... Your hot and cold water supplies will feed the valve that came with the 500058 kit. That valve has two outlet port. One will go to the tub spout, the other now goes to the inlet of the diverter valve. You'll use the supplied cap to cap one of the three outlet ports on the diverter. One of the uncapped ports will go to the fixed shower head. The other port will go to the Danze wall outlet which in turn will feed the handheld. The Danze 4-port diverter affords you the opportunity to feed just the handheld, just the fixed shower head, or both simultaneously.

I just went thru a similar experience this weekend. We had purchased a 6 inch sunflower type and came to realize we don't have the water pressure to support it. Determine in minutes how long it takes to fill a gallon jug. I determined my water output was 2 gallons per minute. the sunflower unit I had was 2.5 gallons per minute. Sounded close enough. I snapped it in and the water ran hose like out of the sunflower, just didn't have enough pressure to dispurse water thru all the holes at a steady enough stream. So maybe doublecheck your pressure to see if you can support either fixture. Just a tip I learned htis weekend!

I used a no drill rain head, hand held diverter shower that attached to my head shower arm in minutes with no need to drill the bottom of the slide bar to the wall. Mine I found at Costco for a bit less than $100. I have seen very cheap, under $20 ones at Walmart too. You can use either head alone or both at the same time. mine Link to walmarts cheap one https://www.walmart.com/ip/PowerSpa-Drill-Free-18-Stainless-Steel-3-Way-Shower-Slide-Bar-Combo-Chrome/33844081?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227040499328&wl0=&wl1=g&wl2=t&wl3=95815173977&wl4=pla-234780536177&wl5=9003316&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=33844081&wl13=&veh=sem

Thanks much and beautiful showers! I am confused about the thermostatic valve. Is this something that I can buy separate and have it installed in the wall so that anytime I change out the shower handle/trim/valve it will automatically be there and still be accessible if it breaks and I need to change it? I hate to have more moving parts and things to break inside the walls. LIke this (although it looks like part of this would stick out of the wall?-another hole?: https://www.amazon.com/Rozin-Thermostatic-Mixing-Temperature-Control/dp/B01FAGWKTC/ref=sr_1_3?ie=UTF8&qid=1542006430&sr=8-3&keywords=thermostatic+control+valve#customerReviews  Or does do certain valves come with it like this?: https://www.amazon.com/Hansgrohe-04231000-Thermostatic-Control-Diverter/dp/B07FDFK5SM/ref=sr_1_1_sspa?ie=UTF8&qid=1542006430&sr=8-1-spons&keywords=thermostatic+control+valve&psc=1 I was wondering, also, it sets the temp but the initial issue of being cold while the water warms up since it has to run through the pipes would still be there, right? Problem is, I have chosen champagne bronze and if I need to get the thermostatic control valve built in I think that will be hard. I'm already having a hard time finding a handheld and shower head built into the same. I might have to get a separate handheld to divert water or I'm back to the initial question of do I just push the shower head over to shoot towards the wall before I turn on the H20 or go back to the idea of moving the control valve? Here's one of the options I was looking at for a showerhead before this discuss that I might need to adjust: https://www.amazon.com/58471-CZ-PK-H2Okinetic-4-Setting-Handshower-Showerhead/dp/B009MLXJN8/ref=sr_1_2?ie=UTF8&qid=1542006748&sr=8-2&keywords=shower+head+combo+with+handheld+champagne+bronze