I have to switch constantly between Write and Engrave mode when adding fingering; first to enter the fingering, then to adjust the inside/outside slur position. Would it be possible to have this option in the same mode?
You could enter all your fingering in Engrave mode and adjust the position at the same time? (You can’t use the popover, but you can just enter fingering directly in the properties panel)
I don’t think I can enter fingerings in Engrave mode.
Ah yes, via the properties panel. Yes, that is an option, although I cannot use the arrow keys now to move to other notes. I will have to select 1 note at the time, not ideal.
If you have Dorico Pro and always want fingerings to go inside/outside slurs, there’s an Engraving Option for that, on the Fingering page, Position section.
Dorico maxim #1: if you find yourself changing the same property time and time again, go looking for a default setting; chances are, there is one 
Or, try to adjust your workflow so that you add all your fingerings (and other notations) first, then switch to Engrave mode to tidy everything up.
Yes, that is what I do now, having Dorico 5.1 Pro. Ideally, I would enter the fingering in Write mode, then go to Engrave mode to adjust things, but in reality, while proofreading a piece, I need to change the fingering often and then need to adjust it again in Engrave mode. What about having a key shortcut to switch the inside/outside slur setting?
Can you share some examples of where you’re needing to override the Engraving Option?
If it’s a lot of times, it’s possible that a better solution would be another option to accommodate your requirements.
It’s not a specific situation, but a workflow approach in general. For example, in this section, the fingering sometimes appears above and sometimes inside a slur, pushing the slur far up. So, I then need to adjust it inside Engrave mode to get it outside the slur so the slur goes lower again.
It would be nice if I could do both Fingering enter and placing above/inside a slur in a single mode. I know that I am supposed to enter everything in Write mode, then continue the layout in Engrave mode, but sometimes I need to change the fingering during a proofreading/playing, and its position, and this can be very time-consuming when needing to switch constantly between Modes.