I suggest breathing exercises
You start doing them
make sure she sees you and asks you what you are doing and why
;-)
dont offer them to her - in the begining
tell her grown ups do this, it is called
Yoga Breathing.
''we do it to be strong and well'' ... or whatever terms you chose
prepare alone, then you do it for her to see (like she caught you at it)
;-)
and after a couple of days of her seeing you do it show her
and let her do it ''as as a favour'' ...
then build it (laid back) as a new habit
the comfort of focus on the nostrils will sooth her ,,, as will the deeper conscious breath
I suggest making up a story (about the breath going in and out) that she helps you create
give it a colour name or character depending what she says about here nose/how she feels about touching her nose etc once she starts it
at first breathe in and count it
pause
breathe out and count it
pause
Praise her for doing it
be impressed that she can /does anything close to it
;-)
see which nostril you want to foucs on
you can make this alternae if / when she is able
this can distract her from the finger
and remember if she goes back to her habit would make it impossible to do the exercise!
NOTE
for later...
slower exhales are best for tension
slower inhales for feeling sad
namaste!