Hi,
I have a tabbed form. The user fills out the form and then the approvers get a deep link to the tabbed form to approve and update a few other fields.
On this form, the Vendor Number on Tab 2 needs a formula to pull the vendor number if there was an input by the user in the first tab of the form "Existing Vendor Number". IF there was no input in this field by the user then the approver should be able to manually enter one. IF there is already an input in the field by the user, then the approver should be able to update it/correct it.
Tab 1 where the user inputs are:

Tab 2 where the approver will need to be able to make edits and submit:

Right now the Vendor Number field has a default property of Parent.Default.
Any help in getting this formula together will be appreciated.