re: How hard is the jump from one child to two?

You’re going from zone to man to man coverage.

At least you won't have 2 in diapers at the same time.

Going from 1 to 2 was much harder than going from 0 to 1 for us

Puh-lease. 2 kids is a cake walk.
3 kids is easier than 2.

Now, the problem is when they are teen agers.

I have two kids, 5 and 2. They're 3.5 years apart.

In my experience, the second time around dealing with all of the things that a baby and young toddler do/go through is much easier because 1) you have a frame of reference and experience to know how to deal with things and how long they last and 2) time absolutely fricking FLIES now. Whatever phase your younger kid is going through, it'll only be a few weeks. And that is a blink. Weeks blue together now.

But. BUT. With their power combined, they are much more difficult than one kid, obviously. I have little energy or time to give a shite about much else but the things I absolutely care about the most. My household absolutely takes all I can give in that regard.

Nothing to worry about. I have 5 ranging from preschool (4) to law school (24). Aside from needing a bigger vehicle, larger grocery cart, and more extracurricular activities to attend, I never really noticed difficulties or stress adding more on. My sister also has five and shes of the same mindset.

Don’t get me wrong, some days it can be a lot - but the good far outweigh the bad.

I found the jump from one to two kids to be huge. I did my part with the first, but my wife was the primary caregiver and I had plenty of "me" time. That went away with the second kid. The remark about switching from man defense to zone is true, but also Dad has to play the whole game now instead of subbing in. By three, you were a seasoned vet so no big deal.

The new baby will be easier because you know what to do, know they aren’t breakable, won’t get worried over some of the small things, etc. The more difficult part imo will be attending to the 4 year old and giving her what she needs while the baby is taking up so much of everyone’s time. How easy it will be is really largely dependent on the 4 year old.

I'll add for OP, I think continuing your level of activity if you can will be helpful.

We do a lot. We go out to eat a lot with a 3 year old and 2 seven month olds. We all go everywhere all the time. But what I've found is it's not THAT much easier not to do anything. Thus far, it's made our kids flexible. Getting three small kids in a car is probably the worst part of my life, but it keeps them occupied and keeps you in the practice of being active and social and I find it more rewarding. The days and weeks pass a lot quicker and we don't really feel like we've missed out on much.

Everyone being mobile is the next phase and it's daunting, but we're going to try and keep up the pace as much as we can.

well I went from married to divorced after the second one so pretty difficult