I'm looking for ideas on how I could get Zoho Inventory to signify that a purchase order # is already used from an external excel sheet. We offer custom services that we are not planning to enter in Zoho. Those services are assigned purchase order numbers and entered into excel but not into Zoho. We want to know if Zoho can look up the purchase order #'s from the excel sheet to let us know that the number has already been used to avoid duplicates when creating a purchase order on zoho.