My uncle passed away unexpectedly 4 years ago. Also 4 years ago, my fiancees father whom he was extremely close with passed away after having complications of health problems.
We know they'd be proud of us and we want them there as much as we do everyone else were planning on inviting. We wanted to set aside not actually aside but more or less 'reserve' two seats and put their picture on the chair my uncle will be on one, fiancees dad on the other at our wedding.
I was told I'm quite crazy for thinking up such an idea.