I don't know the answer but I have to ask you: are you sure you want to do that? Most people create multiple google play accounts because they don't want Google to link them with each other. So, if one of their accounts get banned, they still have some other account. If you link many google play accounts to admob account, and Google decides some app on one of your accounts does something that they don't like, they might ban all your accounts and take all your revenue from you.