Today it is not possible to set customernumber in litium for persons or organizations if they are created in litium backoffice. It is not possible when you create the person/organization and it is not possible to change.
you could ofcource create a custom field for that but that isnt integrated into the checkout flow of litium and litium accelerator.
It should be possible to at the least set customer number when you create a entity i customer module.
This ability was shipped in Litium 8.12. 🎉
any updates on this since it doesn't look like this made it into the Litium 8 release.
I many smaller B2B project we create customers persons and organizations in litium but need to be able to control the customer id since the customer number exists in ERP but isnt integrated, Until you enable edit for customer number or add option to set customernumber when created we need to add extra field and via database set the customernumber from this field after the entity is created.