It would be helpful if there was a notification or a warning that the order is for Northern Ireland so that Customs Information can be added as this is a requirement from the UK.
Thank you so much for reaching out and for being a part of our community. You might be able to accomplish something similar to this using Automation Rules. You can use Country for criteria and you can assign a specific service to orders that meet the qualifications or you can assign a specific tag to the order.
-Erin: Your Friendly Neighborhood ShipStation Community Manager