I have a Marketing cloud org that have only one BU and that is connected with SF Production environment, Now we want to make this as a Child and want to create a new parent BU so can we do this without breaking the functionality like the existing journey, automation, integartion etc?
What you want to achieve is not possible. EID is the only Business Unit which can't have it's hierarchy changed. It will always be the root of the BU tree structure. This is exactly why I always recommend to start with at least two business units:
- EID: This should purely be used for admin purposes and handle data integrations, distributing the "inbound" data to child business units utilising a.o. shared data extensions. No marketing operations should be handled here.
- Child BU X: This will represent your market, brand, or however you manage your digital marketing organisation. Here you will build your assets, journeys, and hold contacts/subscribers who have a relationship with this particular BU.
When you come to a point, where you want to enable a new market or brand, you will purchase and create it as a new sibling to BU X. You will replicate the data model from BU X, and ensure the appropriate filtering of data into each of these BUs. Do keep in mind, you don't need Multi Org connector, if connecting a single SF Org with multiple MC BUs.