Summary:
an older child (in school) is 99% of time OK with the fact that sometimes he gets to go to school on days the younger child stays at home. This includes 100% rational agreement from him that there are good reasons for that.
Sometimes (rarely) on those days he would have a major meltdown and refuse to go to school when it's time to leave, specifically because the younger one stays home.
What's a good way to handle such meltdowns?
Details:
We have 2 kids.
Older one is in elementary school. They have only a limited amount of days allowed for absences in school year, all of which we usually use for sick days.
The younger one is in preschool (meaning there's no such restriction).
Moreover, school and preschool do NOT share 100% days off.
In practice, it means that:
When the older kid's school is closed and younger isn't, we keep them both home (for good reason[1])
When older kid's school is open and younger is closed, younger one stays home but older one isn't.
On some of the latter days (not all), the older one has major meltdowns right when it's time to go to school, and refuses to go.
What's a good way to handle such meltdowns?
The meltdowns are extremely impactful, because being late for school costs him tardiness points (that detract from his available off days); AND there are health risks to leaving for school after meltdown for him.
Important notes:
100% of time outside those meltdowns, the older one is 100% in agreement with us that it's correct thing to do. He knows very well all the reasons for it, can recite them back and agrees with them.
He never voices any issues until it's time to dress for school on those days. As in, we would have a conversation 1 hour before about it, and he would calmly reconfirm that yes, he knows the younger one will stay home, and he's fully OK with it.
He almost never has before-school meltdowns on OTHER days (when they both have to go). I'd say "younger stays home" account for ~80% of meltdowns before school.
It's not simply about "we have to separate instead of play together", because he never has issues when attendance is reversed (he stays home and she goes).
He has some sibling rivalry and jealousy issues in general, but they aren't endemic. But he's very receptive to reasoned arguments over what is and isn't fair.
Footnotes:
[1] We get to pay less for preschool for that; AND more importantly it saves whichever parent stays with them ~1-1.5 hours of commute time..