Large family trip

It has been a long time since I have been in Ireland so no suggestions there but I have travelled a fair bit in family groups. I would suggest trying to find a large air bnb/ house type rental where you can all get together in the evening or for meals and separately plan activities by smaller family units, age or interest. Organizing 14 people including toddlers and teens to get somewhere in a timely manner would be kind of like herding cats. It takes a lot of time to change locations and moving that many people you will end up giving up a lot of your vacation time to the logistics of moving- packing, unpacking, check in/out, driving etc. I would find one group location for a week and then maybe go somewhere different for the balance of your time. Last winter we took our kids and their SOs to Costa Rica, we were a group of 7, including 5 in their early-mid 20s. All cooperative and happy to travel, get up early etc but it was a lot of work and planning and we only stayed in 2 locations,4 nights each. We scheduled most of our days so everyone knew what to expect and when there was their own time for exploration or independent meals and once the kids all headed back to school and work, my partner and I then had a vacation on our own!! There is a great deal of planning and logistics involved with travelling with a large group and wide age range and it can be really enjoyable but everyone needs to be on the same page with similar expectations.

Quite honestly, Ireland would not be my first choice for this group. It will be logistically challenging. Public transportation isn’t great. If you rent cars, you will need at least 5-6 cars to fit everyone, with luggage and car seats.

If the kids were bored at castles in Germany, they will certainly be bored at the Cliffs, Barney and driving the Ring of Kerry.

I would pick one location with great public transportation, lots of activities, and lots of day trip options. Expect the group to split up and do what interests them, not be marched from site to site. Paris or London come to mind first.

Already did Paris and London, lol. Honestly, we don’t enjoy the large congested cities or public transportation with all the kids.

We did Tuscany last year with the villa and rental cars which worked out great - was hoping for a similar experience like that in Ireland.

I would do a search on AirBnB for anything that will suit your needs and work from there, looking for golf courses, etc., within a short drive. If you don't need luxury accommodation, take a look at glamping. You might find a place that you can effectively take over. There is one near Westport House that has bell tents. Some of the places have tiny homes or other options. Little kids love camping. I doubt you'll need 5 or 6 cars as mentioned in a previous comment, but you probably need at least 3, maybe 2 if one is a large van. Do not waste your time on Blarney. There is no such thing as a must-see unless you must see it. Ireland has lots of lovely beaches, which all children love, as well as interesting walks, hikes and playgrounds. One place that is very off the beaten path that young kids would really enjoy is the Sperrins Sculpture Trail in County Omagh in Northern Ireland. This requires a car, and one of the sculptures is accessible only by hiking a long way up a small mountain, but the other two are drive-up, and one is in a large park. Here is a link:
https://www.derrystrabane.com/services/tourism/rural-tourism/the-giants-of-the-sperrins

It sounds like you have 3 family groups. Depending on your budget you could consider Parknasilla Resort, https://parknasillaresort.com/. They have 2 bedroom self-catering apartments that sleep 4 and you can add a 5th child under the age of 12. I chose random dates in late may and it was running around 300 Euros/night. But the nice thing about Parknasilla is that everything is there. Kayaks, pool and golf. It even has a faerie trail that we adults even enjoyed. And it's on the Ring of Kerry. So people who wanted to drive all or a part of the Ring could do so easily.

I had looked into Priory Glamping Pods a few years ago but never pursued it. But it may also be something for you to consider. It's in Killarney and close to Killarney National Park. https://www.prioryglamping.ie/