REviewing this thread, it's been a long battle. Thankfully, you've had time with your dad and he's had time to do things.
Prayers for peace, strength and discernment for your dad and each of you who love him. Trusting in God's will is never easy. We want to do "something...anything."
All we here can do is to continue to interceed with prayer on your behalf.
Lord, be with this family... you helped them beat it once, and according to your will, we ask for your Healing hand again. But thy Will Lord, not ours.
Keep all in your loving arms, Lord. Fill them with the Holy Spirit.