Can we seek guardianship and/or child support in WA state?

My daughter's boyfriend has been living with our family due to family issues in his life. He has lived under our roof for 11 months with no financial support from either of his parents (they are divorced). Can we seek child support from the parents since we pay everything for him? The child support his father would be paying is no longer paid because he is not living with his mother, but neither of them will pay us directly. Thank you.