I have a feeling that this has been mentioned before, but the terms required to describe it are so common that a topic search is not really possible.
Is there a way to write “p underneath the strings and piano” without the Dorico thinking that the second “piano” (the actual instrument) is actually a word and not an expression symbol? It keeps disappearing because of this. I had a chuckle when I realized that, but a solution would be marvellous!
Thanks in advance
Create the “p” dynamic with the popover. Then add the rest of the text with the “suffix” property.
That’s what I did, but it still disappears, though sometimes not immediately
I didn’t hang around long enough to see it go 
I wonder if putting a Unicode zero-width space or a soft hyphen in the middle of “piano” would make it stay. You would probably have to create the text somewhere else, then copy and paste it into the property box.
That’s my solution for now, but I’m hoping there’s something built in. Also, I can use the word "keyboard’ instead (pianoforte would be a bit much! 
)
Could use use an abbrev. like “Pno.” instead of the full word?
(I’m still trying to imagine how you are using this instruction. Perhaps I am misinterpreting the word underneath. )
Provided you don’t edit the dynamic again, e.g. by opening the popover, you should find that the “piano” text remains in the Suffix field, but if you edit the dynamic again, the text will be reinterpreted, resulting in the “piano” being (in this case unhelpfully) interpreted as an actual dynamic.
Excellent! Thanks a bunch