So much harder.
We have an elder, then DTwins. I know twins make it disproportionately harder, but it's not the extra cost or sharing your time/resources at home as such, it's the way the world is geared up to families of 4 and under.
Table out? Seats 4. Family ticket? 2 adults, 2 kids. Hotel rooms? 2 adults, 2 kids. Three car seats across the back, then fitting everyone's paraphernalia and pushchair in the boot? Pain in the ass.
Two children can comfortably share things, a sofa, a room, whereas three can't. So many games are player one Vs player two, and so player 3 is always sat out for any of those.
Then there's the simple logistics of adults being outnumbered. All 3 are crying? Which one has to wait to be picked up and comforted?
That being said, I love our larger family, and whilst the twins are extremely difficult, they are extremely amazing in equal measure. If we'd had them first, no way would I have chosen another child on top. It is lovely at Christmas when we seem like such a house full, before anyone else even arrives.
Think hard though, because whilst there are beautiful moments, there are many "Jesus Christ why have we got so many children" moments too.