I’m fairly new to the game having only started playing it for just over a month now.

What I want to know is,
If I build seats in the stadium, does the seating remain if I then upgrade the stadium or would I have to build the seats back after the stadium upgrade?

I currently have a small town with no seats and wondering if it is worth building seats or not, as I don’t want to waste money building seats if they disappear once the stadium is upgraded.