PADI Specialty Instructor Manual - Dry Suit Diver - Page 22 at the very top:
1. BCDs for use with dry suits - although under most circumstances you maintain neutral buoyancy underwater with your suit (more on this later), you always use a BCD when dry suit diving.
a. The BCD provides emergency buoyancy if you get a substantial leak in your suit.
b. The BCD provides a more comfortable way to float at the surface.
c. Choose a BCD that fits over your dry suit - the one you have will probably work, but you may need to readjust it - and that does not cover or interfere with the suit valves.
Page 26 - Special Note - Overweighting is the number one cause of problems when dry suit diving. Take the time to determine the amoutn of weight you need.
Page 26 -
4. Adjusting your buoyancy underwater.
a. Underwater, you add air or argon only to the suit. Do not use your BCD.
1. This avoids a suit squeeze (severe pinching due to the compression as you descend).
2. You’re not having to control two systems - adding or releasing gas as you change depth.
3. It keeps the proper amount of air/argon in your undergarment for insulation.
As stated in the previous posts - this is for RECREATIONAL Dry Suit Diving ONLY! Tec Diving takes on the method of enough air in suit to prevent squeeze and then use BCD as necessary - Tec gear is heavier and therefore the dry suit would normally not support the Tec Gear at depth without going into balloon mode.
Bottom line is what actually works best for you when you are properly weighted and equipped.
Reality is that this is not a change from Open Water. Remember, the idea here is to control buoyancy - just like in OW. Difference being you use the Dry Suit rather than the BCD. You are still using ONE item to control buoyancy underwater. That’s how we treat a recreational diver. One item so as to not task overload.
Anything else? I have manuals and will happily look up lots of methods. Oh, I read them all too at least twice so it’s pretty easy for me to find stuff.