I believe what you mean is you want to copy over your current Clan Roster from MW3 or BO2 over to Ghosts. That feature was available during the Early Registration Process of Ghosts, when Clan leaders can simply copy whoever is in their Roster. That feature currently disabled, but will be available on November 5 when Ghosts is released.
It is now confirmed that your members in MW3/BO2 cannot be transferred to Ghosts automatically even now that Ghosts has been released. Ghosts Clans are managed through a new app simply called: Call of Duty. It can be downloaded to a mobile phone or tablet. For now not all phones and tablets seem compatible to it.
Since you missed early registration/migration of roster you would have to do this yourself. It will take time, but it is possible.