Auto populate form based on unique value

[theonlyhamish]

Hi folks, im new to this but always learning!

I have a form to add a new record/row, the form has a drop down list linked to another table with the 'Customer Name'.

When i create a customer separately they are given a uniqueID to reference them through the entire worklfow but if i open this form to start a workflow halfway through the process, (which is normal) i can only select 'Customer Name' from the drop down and none of the other customers details are taken across to this new row.  I could set the UniqueID column to form the drop down list but that is just randomly generated letters that wont be recognised.

Thanks