Not sure I understand the question. The 'Excess' coverage applies to all drivers LISTED on the rental contract. If a non-listed driver is discovered driving (either through a ticket or accident) the contract (and ALL insurance) is VOIDED and the person listed on the rental contract is personally responsible.
Third-Party Excess coverage is available from a few other outside sources, but there is only one that I know of that covers Non-Eu citizens. See: https://www.moneymaxim.co.uk/faq/car-hire-insurance/non-uk-residents-expat-car-hire-insurance
Some rental car consolidators like AutoEurope and Expedia DO offer a Third party 'Excess' cover. So, too, do SOME Trip Insurance policies.
However, Car Hire companies do NOT fully accept most Third-Party Excess, so their rules (and Deposit policies) listed in their "Terms & Conditions" for Waiving Insurances would apply.
__________________
Bob
Help Us to Help You. The more you tell us about your plans (dates, interests, budget), the better we can tailor our advice to suit!
In order to qualify for cover the person named as the lead driver on the Car Hire Excess insurance must be the person shown as the lead named driver on the car rental agreement.
You can include up to five additional drivers as long as they are also named as a driver on the rental agreement.
You and all additional drivers must be aged between 21 and 84 years on the date of purchase of this insurance and must have a full valid driving licence or hold a full internationally recognised licence to drive the rental vehicle.
You and all additional drivers must be permanent residents in the Republic of Ireland.
Actually, there ARE 'Excess' Policies available to non-Irish (but EU citizen) renters and, at least one company that offers coverage to citizens of the USA.
__________________
Bob
Help Us to Help You. The more you tell us about your plans (dates, interests, budget), the better we can tailor our advice to suit!
As they say, the devil is in the details. Unfortunately when renting a car in Ireland you must plow through tons of fine print to figure out what deal is best for your circumstances. There are also many fallacies presented as facts all over the Internet. Never take one persons word for something important. Do your due dilligence and check and recheck facts. Also, things can change quickly. Today's info can be changed tomorrow by any car company.