Father and Son Family Member Visa refused

Hi,

My Italian friend has applied for his father family member visa, at first it got refused asking them to send proof of that they really were father and son, they applied again attaching a copy of his birth certificate.
He did the biometry and was waiting his Residence Card, but instead he got another refusal, saying they failed to proof his father was a financial dependant of him.

How can I cancel this application so they can do another application, but through his wife now, not his son.
When they apply for the first time, she wasn't working so they couldn't apply through her, now she is.

Whats the best option now?