Buying inner envelopes for invitation separately to write out plus ones

We didn't include an inner envelope, and just wrote "and guest" on the outer envelope.

For the single mom and her kids, I would put:

Ms. Smith and Guest John and Jane

I definitely wouldn't spend the money on two extra invitations (and four extra stamps) to send separate invitations to the kids since they aren't adults

I didn't include an inner envelope when I ordered from Minted.

I wrote "and guest" on the outer envelope.

And with kids... I wrote Mr John and Mrs Jane Doe and on the second line wrote Johnny, Katie, Billy, Their names were a bit smaller, but no big deal. Better than spending a ton more money... when we all know we'd rather spend it elsewhere :-)

Thanks for the advice, ladies - I feel like I have been overthinking this!

It's very difficult not to drown in the details. Try to remember that people aren't going to remember the teensy details that you notice - they're going to remember that they came to watch you get married, ate and drank their fill, and generally had a good time