Edit text on a Formula column?

HI, hope you can help me with this.

I have a column formula that brings data from another table’s related column. The client type. I want to automatically have the info populate in the Client DB when I add a project in the Project DB. This I managed…But… I want to be able to add another ‘client type’ if this is empty on the Clients DB…, but I don’t manage to get this working . Is it possible to have a formula that lookup data and if it returns empty or , to be able to edit it and add text?
This is what I have so far:
thisRow.[INCOME - JOBS - ORDERS].[Client Type].Unique()

Thanks in advance!