There is nothing in the Etihad T&Cs about merging accounts or whether you are allowed to hold multiple accounts.

I would advise you to ring them (if you ask EtihadHelp here I predict they will just ask you to send your details to the usual email address) and see what they propose.

However, I really think you need to contact your credit card company, too. Unless you abandon your existing account, they will keep sending your miles to the "wrong" account.

Please report back!