Am I being unreasonable? Seating chart & dress code.

Background: no one in my family has had a super big/structured wedding. My mom had hers on the deck of my grandparents house, my aunt had hers in a community hall where she wore jeans, and my uncle had his in Hawaii and I believe it was an elopement.

My fiancé and I are planning a bigger wedding (140 people) for the end of May next year. My fiancé has been dreaming about this day for years since he worked at a catering company that catered so many gorgeous weddings.

Keeping this idea in mind we are planning on asking guests to wear semi-formal/cocktail attire as well as adhere to a seating chart. We are inviting several people that don’t know many other guests and we don’t want them to feel alienated or awkward trying to find a seat so using a seating chart we can pair them with people they have common interests with and it also helps people connect with others they might not have ordinarily sat with.

We had a family dinner with my fiancé Sunday night and my aunt asked about how the wedding planning was going. I described the event vibe we were going with and got what I would describe as a weird amount of pushback. The quotes were as follows:

Mom: you are so controlling by having a seating chart. We will definitely be doing some seat shuffling.

Uncle: well I am going to be wearing a Hawaiian shirt and cargo pants. That’s what I wore to my wedding and I’m not dressing nicer for yours.

Aunt: I want to invite my extra friend sue! She can be my plus one! (Her plus one is her husband and when I pointed that out she said “ok a plus 2!”)

I asked them all not to do this but I felt very brushed off. This whole debacle kinda stressed me out and I don’t feel like I’m being unreasonable but am I? Should we loosen up our dress code etc?

TLDR: family disagrees and plans to actively not follow dress code and seating chart. Should I loosen up?