To share data, both services need to be on the same account number. Unfortunately there's no way they can recognise each other and share without it.
If both the accounts are under the same name, you can contact Optus to consolidate them; but if not, then you can complete the change of ownership request here to move both accounts into the same name. From there, there may be an option to move the service to an existing account number, or you may still need to consolidate them once their in the same name.
Hope this helps