SEN DC does add to it, and having jobs that require international travel (so keeping on top of everyone's schedule is ridiculously important - we've only twice had to work it that DD had 1 parent in the house going to sleep and a different one in the house when she woke, as 1 arrived home after midnight from their trip and the other left on a 6am flight for their own!).
Both DH and I also have roles outside of work which involve organising other activities (I run 1 youth group for 21 DCs and am group secretary to the wider group involving 170 youth members; and am the class captain for a different youth group of roughly 20 DCs which involves recruiting and overseeing their paid instructors, and am on the Junior Committee across all classes in that organisation (responsible for a range of activities for over 200 DCs) - DH is involved as the national chair of a committee organising activities in over 25 clubs for over 300 DCs and dealing with international issues on that front, and also has a role in 2 professional organisations relevant to his work including committee work and organising events).
So there is the juggling of calendars and making sure that DH and I both know important dates in advance (and making sure DD tells us these with more than 10 minutes notice!).
Paying the bills - lots are DD but a few are not. But I do have the main ones in my budget on excel, including the annual ones (expected amounts and dates) to watch for.
Organising the maintenance - plumbing and electricity issues as they arise, getting boiler serviced annually, getting cars serviced or repairs done, getting chimney swept annually, defrosting the freezer, degreasing the drains etc.
Remembering the regular jobs that need doing - making sure we remember to check oil and tyre pressures frequently enough, agreeing the fortnightly cleaners visit (they call each time in advance) and being prepped enough for that (having the clean sheets out to be changed, having the correct bin liners out as different ones fit different bins, leaving the kitchen drainer clear of dishes as we usually leave things air-drying, and just putting away the piles of clutter to allow the actual cleaning to happen). Checking the outside drains (1 has a tendency to being blocked from further up the street but there are 2 that need checking) so a major blockage doesn't happen. Checking smoke alarm and CO alarm batteries.
Booking DD appointments, filling in forms, chasing others on phone during their very limited "available" hours. And then organising time off to get to appointments. Filling her script on a monthly basis.
Making sure there is food in the house, that is edible, and what people will willingly eat. Taking account of changing tastes (remember the SEN? There are food issues included!). And the diary, meaning evenings that we are only in late and starving, or need to eat and get back out again, or that DH is in charge and won't cook properly (midweek at least) - or other evenings that we can cook properly and have time to prep for the following day, or DH is not so busy so will be OK to cook a meal, …..and having different meals to deal with the different needs, thought about, agreed, and shopped for.
Dealing with my health issues (long term, chronic condition that I need to manage and ongoing pain from other issues), and DH's (different kind of long term stuff going on). Both of ours are exacerbated by stress and tension - so they are always flaring up!
Extended family admin, around older DPs (mostly DH in fairness, but I am anticipating some issues getting worse for my own DPs in the next couple of years and some things already do need time and energy to think about and help resolve at a distance).
For us, closing the door on Christmas Eve to the world outside, having no commitments to others (apart from seeing a few people after mass on 25th for a drink) for 36 hours, and putting away all responsibility for admin for others as well as ourselves, is SUCH a major relief. We keep saying we need to slow down, but can't see any others who will take on some elements of what we do (we have both asked, in general and for specific tasks, and got little or no positive response). But it all gets done, somehow.