grandsophy,
Since this is the HOD Board, I guess I'm just wanting to clarify if your oldest child to whom you are referring is currently using HOD? If you are underway with HOD, hopefully the further you travel on the HOD path, the more there will be to love about school. One way to make school more joyful from the perspective of the HOD Board is to use HOD!
I know this will not fix all problems, but since the purpose of our board is to help you use HOD in your own home, it is definitely a partial solution to consider! I know my kiddos do love their summers and their recesses, but they do enjoy their school days too.
It looks like you are using HOD with your little ones and hopefully that should help bring some joy to their school days. I do think that proper placement in HOD is very key. So, if you are going the HOD route, with any of your kiddos, you'll want to make sure to use the placement chart to be sure that your kiddos are accurately placed. This makes a big difference in how joyful kiddos are about their school, as we want to be sure they have the right amount of challenge without it being too much. If your older child is setting the tone for your days, as the oldest often does here too, I'd encourage you to consider HOD for him/her as well for the upcoming year if you haven't already. I'm not sure what your plan is for next year school-wise but that would make a difference in how we'd advise you.
Honestly, at my house, we've found that our first days have their share of bumps and hiccups, as I am a jump in and swim through it type person. But, by the end of the first week we've truly begun to hit our stride and after that our year in the day-to-day goes very, very well! So, this is why I tend to focus on what you'll be doing for the 35 weeks after the first day, rather than on the first day alone.

We all have attitude issues to work on with our children (and within ourselves), but the selection of what you use curriculum-wise and how you use that curriculum will impact you every single day.
Without using HOD in the day-to-day for your children with whom you have the concerns, any recommendations we'd give for the first day would only help you for that first day. We desire to impact the rest of your year as well.
So, if there is any way that we can help you use HOD in your home with all of your kiddos, which will hopefully help make school more joyful, we are here to help you do that! We would love to have it bring you joy too.
Blessings,
Carrie