In general a will that is valid in the country it is made will be valid in other countries. So a will made validly in Ireland will be valid in many other countries and vice versa. However when you make a will in ireland you will get some irish legal and tax advice which may not translate to other countries. Whichever you choose you should inform the solicitor of your intention regarding assets in other jurisdictions so that they can cover that in the will, even if that means just confirming that the will does not relate to property abroad.