Copy the Parent Account from Account to Opportunity

Hi everyone,

Some of the accounts of my CRM have a value in the Parentaccountid field, indicating which Corporation that account belongs to (Corporations are account records as well), using the standard functionality for accounts hierarchy.

I have created a custom field in Opportunity named "Corporation" as I need the corporation field value to be assigned from Account to Opportunity every time a new opportunity is created. The field "Corporation" in the entity Opportunity is a lookup field that refers to the Account entity.

But after doing that, I cannot create the assignment in the 1:N relationship Account-Opportunity because there's already an assignment between the field accountid (Account) and the field corporation (Opportunity) that has been created by the system when I created the new field. Therefore when I create an Opportunity the Account name value is copied in the Corporation field, instead of the ParentAccount value.

I've tried to delete the accountid (Account) - corporation (Opportunity) relationship but I get an error stating that this relationship is needed by the system.

Is there any way I can solve this and set that assignment between the Parent Account of an Account and the Corporation Field in the Opportunity?

Thanks!