We have custody of a 6 year old nephew from Ghana. We intend to adopt him.The period of time for all of this to be done in over two years. For the boys sake we need to be with him. Can we bring him here on a 5 or 10 year multiple entry visa, have him stay for 6 months, leave for a weekend to Canada and return for another 6 months, until this process is complete.His father deserted him at birth and his mother does not want him. He is currently staying with his grandmother, he know my wife and I as his parents. What do you recommend.
You should consult a lawyer, but let me give you a short answer.
No you cannot legally do this.
It is absolutely prohibited to use a visitor visa to live in the US, and that is exactly what you are trying to do. The brief departures make no difference. Being a minor makes no difference, and nor does being in the custody of a US citizen. Even when you have successfully adopted the child there are still steps to go through for them to legally reside in the US.
I know someone who attempted this, and when discovered he was banned from the US, despite having both a wife and a child who were US citizens. It took the intervention of a congressman to get him admitted again.