Personally I don't have specific songs that automatically equip Daubla over other instruments.
I might be strange here but I always felt more comfortable picking my instrument manually.
I have 3 hotkeys on my G-keyboard. One is for Horn (which is default), one is for Daurdabla, one is for Marsyas.
My standard setup is casting 2 full songs with Horn, then 2 fakes with Daurdabla, then overwrite those fakes with Horn ones.
When I cast fakes, they are "real" songs. I don't use silly songs but the ones I really want to use.
If, say, I wanna give marchx2 balladx2, I'm gonna Marchx2 with Horn, then balladx2 with Dau, then overwrite balladx2 with Horn.
How do I pick the songs I cast first? Depends on what's most needed, what would gain more by being "full potency" from the go, and things like that. I make those decisions on the fly.
I like the freedom this way allows me to play BRD without binding myself to specific/useless songs for fakes.
Also sometimes there are instances where I want to cast all 4 songs with Daurdabla, for instance if party is too spread out or ignoring my signal to gather together.
At least I can give them all fakes and maybe overwrite them with real ones after.
Even if for whatever reason I won't be able to overwrite them, fake songs are better than no song.
Again I might be strange, since I'm aware most people like to automatize this part of playing bard but, dunno, I've always felt more comfortable this way.