Oh, I thought you were directly answering my previous reply.
In that very specific scenario, she can directly shoot Zabuza to force Haku to save him and leave her alone. But maybe Haku needles are faster, I'm not sure
Haku can sense Zabuza in danger.
I'm betting that her mind is faster than senbon, so if Zabuza is caught Haku will immediately go to him to prevent suicide
Ino can split into two.
So she takes one half and makes it roam around until it finds Zabuza. She is very fast because she caught Obito before he could sense her coming and he was long distance away
Ino makes Zabuza commit suicide, thus forcing Haku to take the hit. Then she repeats.
Although Demon Aura might resist her technique, in which case they're screwed.