All services and products used in a record file will automatically be added to the invoice. In the Billing section of the record, you can review all the items and even add new products.
The products synced from the Plan section of the SOAP already come with a defined quantity - in order to change it or remove the products altogether, you'd need to go back to the medical section.
For any new products added in this section, you can edit their quantities or remove them directly from here.
Each item (service or product) will have a provider associated. The default one will be the user that added the item, but it can be updated if needed. This will ensure that the reporting is accurate.