Just Venting- Don't Mind Me

I feel like I should preface this with:
I swear I am a productive human with a job who doesn't usually obsess over the small stuff. But this wedding stuff is difficult.
I previously reported that I was having guest list cutting issues. I tried to get a bigger venue, but they waited 2 months to let us know they could accommodate us. So we already found a different place.
My wonderful fiance tells me "Well, don't really worry about Toby and Jess. They came to so and so's reception, but they didn't come til way later." So my fiance was trying to tell me this to relax. But this is what I heard: "You're working so hard to find space for Toby and Jess and their 7 kids. Even though there are tables of 8, you're trying to make them a table of 9. But that table is going to be empty through all of dinner. Even though we will have paid for at least $80 of food for them. And you'll have had space for some of the cousins and friends you're cutting off your side of the guest list."

I wish there was a way to politely just not invite all of their kids. Tyler and Jess and that's it. But there isn't.

Or at the very least put on our RSVPs:
--Gladly Accepts
--Will be at dinner
--Will be late. We can't make dinner but save us some cake!


And somehow ask if they are only attending the ceremony or only attending the reception or both.
(Skipping the ceremony is totally acceptable in my area and circle.)

I'm just annoyed because right now it looks like I'm cutting 3 friends and 3 cousins I would love to invite.