What I want to do is have a note occurring simultaneously in both voices, tied in an upper voice - but not in the lower one. I made a little demo in Finale to show the sort of thing I want. I can’t figure out how to do this in Dorico.
demo - Score.pdf (56.1 KB)
like in Finale, you use two voice directions.
insert the notes for the first voice, ties and all.
go back to the beginning where you want to have the 2nd voice start.
restart the insert carat.
press"v" to see if your score cycles through different voices.
If it does not, then start a new voice direction - Shift+V - (for this, I’d suggest simply make “voice 1 downstem”)
and then enter your 2nd voice’s notes.
there’s an option somewhere to have similar noteheads overlap (sorry, I don’t have Dorico open right now). Notation Options/Voices/ there’s an option in there for which noteheads should or should not overlap.
*
N.B. don’t forget to press V again once you’re finished entering the 2nd voice, so that new notes will once more be in the default 1st voice, upstem (don’t worry, despite the name, it will place stems in the correct direction as long as there are no notes in other voices)*
@johnwillattplant You might want to enable voice colors (at least temporarily) to help keep track!
The setting to overlap is in Notation Options→Voices. You’ll have to scroll down to get to the appropriate ones. (I don’t think Notation Options affect your entire document, so be aware you might have to change this in more than one place. Someone else can check me on this, or offer a more universal/default solution.) There is also a property in Engrave mode called Voice Column where you can manipulate the note’s location.
— Jim
Absolutely!
Voice colors has got to be one of the most important features of Dorico when you’re starting out. It helps so much to understand what’s going on.
Even after a number of years I find myself switching them on and off at various times to double-check issues I might have related to voices.
I often forget to switch back, then have to filter and switch them! Even in Finale with its layers… 
Many thanks - the option to have the noteheads overlap was what I needed. I was trying to input the tie AFTER putting in both voices - and of course Dorico then could not distinguish between a tied note in voice 1 and the same note, untied, in voice 2.
Thanks also for understanding the problem. And thanks also to Jaskarbong for directing me to the right place!
you can tie a voice 1 and a voice 2 note, but be sure to select both notes when you press “T”.
why this is:
Dorico assumes you are tying to same-voice notes by default. So it will look for the next “same” note to tie to.
You can force it to recognize different voice notes as being permitted to tie, if you specify which notes.
and if you have two noteheads sharing a staff position, click on the stem of the note you’d like to select rather than on the notehead. it’s a bit more finicky fiddling with the mouse, but it WILL select only the note in the voice you want.
Very useful tip! Thanks again!