Several sims have this ability to hold a shift key or button and be able to access a second set of assignments for a particular button. DCS is a very good example of this and they use an assignment process similar to MSFS 2020.
Not exactly sure how you mean this — you can assign SHIFT plus buttons, what are you missing exactly? I don’t have DCS.
What I’m looking for is to be able to assign a Global shift button to assign two commands to the same button. For instance you could assign the Global Shift to Button #1 and then say you assign command 1 to a button #2 and command 2 to a button #2 when the Global Shift button #1 is pushed. This allows any button like the mentioned button #2 to or any other button to have two assignments by having a global shift button assigned in this case button #1. I rarely use the keyboard and have developed muscle memory for dozens of commands on my VKB gunfighter stick and Virpil throttle across 4 different simulators and VR flying. Maybe I’ve missed this capability, let me know. Again I wouldn’t want to use the keyboard for the dual assigning.
Joe
You can’t do it globally, but you could set up the second command on each button using 2 simultaneous presses. You can also use more than 2 buttons for a 3rd command. For example on my old sidewinder stick I have button 3 as flaps up, 4 as flaps down, and pressing 3 + 4 together toggles the parking break.
So you should be able to set things up as you do for the other sims, it will just take a bit more work pressing the buttons as you assign the commands.
Ok, I understand you’re talking about a controller. Makes sense. Actually my old Sidewinder Precision Pro featured a dedicated shift button for exactly that purpose. Was kinda neat, unfortunately they dropped it on the second version.
Thanks. How do you assure when you press 3 and 4 that it doesn’t accidentally issue the button 3 command? Do you just not release the button 3 before pressing the button 4?
Joe
I did think about that before setting it up, I but if I’m setting or releasing the parking break I’ll be on the ground and it doesn’t matter if the flaps change a notch…
I guess the way around it is to dedicate a button to “shift” and not assign any command to it, then use it the same way as a a keyboard shift, press it first and then the 2nd button press will issue the command. Just be sure to release the 2nd button before you release your assigned shift button.
The more you can avoid touching the mouse, the more immersive a simulation becomes. I too fly DCS, and am not aware of the ability to make a shift key within the sim. I do this with my CH Products using their CH Control Manager software (which has not been updated in years, unfortunately.)
Using my old CH Yoke and Throttle Quadrant in P3D, I can create a specific profile for a specific aircraft and not have to touch the mouse to startup an A2A Accusim aircraft. I like to make the fuel selector switch SHIFT to fuel pump on and off for priming. To do this, I need to use the CH Devices in Mapped mode, which MSFS seems to not recognize.
Geez, you certainly have a point there. Now in MSFS it happens to me all the time, I try to manipulate some control with the mouse wheel, and just the slightest cockpit shake will turn that into an unwanted zoom action. It’s actually why I always hated VCs. They might look nice, and granted they look better than ever before in this sim, but I just hate to operate them. Those good old 2D panels certainly had some advantages in this regard IMHO. Now fire away. 
Just into the mouse controls and clear the wheel zoom assignment and any other things that were auto assigned that you don’t want.
Joe
You can definitely do this with SPAD.neXt interfacing between the controller(s) and MSFS.
Thanks I’m aware of that and used SPAD.next for many years, I now use LINDA and it’s just been made available for FS2020. What I really was asking was for the ability to be built into FS2020 like it is in DCS for example.
Joe
Add the ability to bind multiple key strokes to expand the possible key binding number for all controllers. Similar to the system that is used in DCS.
ehm, as far as I know this is already in.
I’ve bound ALT-SHIFT-R to ‘refuel and repair’ to complete the bush flying challenges. It worked without problems.
Are you using the right or left shift key? I’m having all kinds of problems when I use the one on the right.