Bollocky bollocky bollocks

Trying to renew the kids UK passports & having major problems with the UK passport office as the kids have Irish passports too. Now this shouldn't be a problem, but the Irish passports only show their first 2 names & they all have 3 - which means that the UK passport office rejects the application. Their advice is "get their names changed on their foreign passports" but as the Irish passport won't, this leaves me in a pickle.