Mixed POV probs

When a story is told from multiple points of view and the main characters are different ages - as in daughter, mother, grandmother - what age will the readers be?
I think it depends on:

• main point of view
• story content
• readability

What matters most?

The story I'm writing is told from 3 points of view:
Dani (13 yrs) 1st person
Esme (her mother) (30) - 3rd person
Frances (grandmother) (60s) - 3rd person

Dani and Esme are the two most important characters. Esme has the most 'story' i.e. plot, but Dani's is the viewpoint that matters most.

What's the age range that I'm writing for? Is it YA or adult?

I've thought of making Esme's the most important point of view. That would solve the readership problem, but I prefer it to be Dani. That's what the story seems to demand.
And now I'm off to rehearse for our Blue Rumour gig.