Is it possible to merge the customer and supplier into a single party ID or accounts with sites?

Summary:

We have a single organization created twice as two different parties (Party IDs) as a supplier and a customer. Is there a method to merge the supplier Party ID and the customer Party ID into a single party that has both supplier and customer accounts?

Content (please ensure you mask any confidential information):

E.g. 

1 Organisation: Org1

Supplier record 

Org1 PartyID = 123

Customer record 

Org1 PartyID=456

We want both to be on the same party ID

Customer record and Supplier record

Org1 PartyID = 789

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):