No children at wedding on invitation?

I think some ppl may take offense but like u said the #s add up quick. You can't please everyone. I would make sure you properly address the envelopes Mr and Mrs (not the Jones family).. If you write "adult only" reception the family members may get confused if their kids are invited..

Just address each invite to who you are inviting.

Mr and Mrs Jones or the Jones Family.

You wouldn't. You would address the invite to Mr. and Mrs. Smith. If you're really concerned you can always write in "We've reserved X seats in your honor" on the RSVP card.

How are you doing RSVPs? When I was researching a similar issue the solution I liked best used the RSVP to make it clear without being rude. Things like listing each invited individual with a box next to their name for their meal choice (kind of a pain since each RSVP needs to be unique) or having the RSVP card say something like the "X seats" suggestion from @Emily.

We had rsvp on our wedding website and people saw it there. We ran into maybe 1 person who asked us questions about why they can't bring their kids. Other than that majority of our friends were excited for a night out to themselves.

You never list who isn't invited. Just address the envelope to those invited.

List reception as rated M for mature. No kids allowed... When given enough notice they'll get a baby sitter. However, if you really want them there reach out and explain. It'll be fine.

My FMIL insisted on hosting a second "reception" for us a month after our wedding. I haven't seen the invite, but I heard it says "adults only" AND lists our registry :-/

To answer your question, I would only address the invite to the adults and put how many you are inviting on the rsvp e.g. "we have reserved ___ number of seats in your honor." Also, try to spread it by word of mouth.

This is the language I'm using. I'm still going to write in how many seats and addressing the envelopes with who exactly is invited. I don't need any confusion

You will probably upset a few people but it's your day. Noone else's. I would politely word it "adult only reception" on the reception card that people send out with the wedding invitations.