If Knox and Sollecito's conviction is over-turned, they go off and live their lives, no money is paid to the victim's family.
If Knox and Sollecito's conviction is upheld, they go off to jail for the next 20+ years. Someone has suggested that they can become millionaires in jail, but why would they do that if all their earnings will go to the victim's family? Furthermore, how does someone become a millionaire in jail?
Either way, there is no compensation to the family, so to suggest that the lawyer for Meredith, the victim, has a financial motive to see the convictions upheld makes no sense.