Hi H-TS,
I totally get where you’re coming from. For overseas suppliers that don’t have an ABN, that warning can end up being more annoying than helpful. The option that’s available is to turn that warning off in Purchases for the whole file. You can do that by going to Setup > Preferences > Purchases, then unticking Warn if Supplier Does Not Have an ABN for Purchases Greater Than $75 Tax Exclusive. If you’d prefer to keep the warning on, I’d recommend leaving the ABN field blank for those overseas suppliers rather than entering a random ABN, just to keep the card data accurate.
Regards,
Sai