Is it an unreasonable request to suggest going to my mother-in-law's house for about 30 minutes on Chuseok day before heading to my grandmother's?

I am a husband with an 18-month-old baby.
My parents' house (hereafter referred to as my in-laws' house) is in a neighboring city about 30 minutes away from our home.
From my parents' house to my grandmother's house is a 10-minute drive.
Since both my grandmother and grandfather are still alive, all the relatives gather at my grandmother's house during the holidays.
We usually go to my grandmother's house on the morning of the holiday.
My father has passed away, so it is just my mother.
Regarding the holidays... from our baby's perspective, my parents' house is the "in-laws' house," so my mother's position is that we should stop by our house for about 30 minutes before heading to my grandmother's.
However, my wife's position is that we should just go straight to my grandmother's house.
My wife's reasons are:
1. We would have to leave our house 30 minutes earlier, so the morning schedule is too tight. She feels I am being inconsiderate.
2. Why do we specifically have to go to the in-laws' house?
3. When we go to my grandmother's house, I have to go to the ancestral graves to pay respects, which means I have to watch the baby alone for about an hour and a half, and she finds that too difficult.
To be honest, I don't understand.
It's just a matter of whether we leave our house at 9:00 or 9:30; why is the schedule so tight?
And from our baby's perspective, since my parents' house is the "in-laws' house," I suggested we stop by for a bit to get used to the environment before going to my grandmother's (we don't see them very often; it's about once every three weeks. I have a lot to say about this, but I won't write it all here).
As for her saying it's hard to watch the baby for the hour and a half while I am at the gravesite—then what am I supposed to do? Am I supposed to skip visiting the graves? Is that something I can just decide on my own?
This is roughly the situation, but actually, I think I know why my wife is acting this way. It's because her older brother has a disability, so we do not visit her parents' house. I haven't gone there in several years, and our child has never been there.
I suspect she feels resentful, thinking, "We don't go to my family's house during the holidays, so why do we have to spend so much time at his side?"
But is what I am asking for right now a particularly excessive demand?
Every time this happens, I sincerely want to get a divorce.
Life is so uncomfortable and difficult. I'm constantly stressed and walking on eggshells.