I have 3 kids..and all 3 of them can fall asleep at the drop of a dime, This is not because they had a specific nap time or bed time.
You left - that was your choice. My children would have just fallen asleep on the sofa and then I would have just transferred them from house to car to bed. i know that other people would say "my kids would NEVER have slept through them coming home, being transferred from a car seat to a bed, etc". Well - maybe because you never tried it, My kids could always do it!
I think this is a little unfair - it may be different parenting style, as you suggest, but it may also be different 'childing' style. If all
of your children can 'always' do it, you're lucky. I had one child who could do it, and one who most decidedly could not
, and I don't for one moment believe that I changed my parenting style between them. I belonged to the 'be relaxed, no set schedule' group, and the Elder Chick wasn't bothered when his meals came as long as they came, wasn't bothered where he slept, but when he slept, he wasn't having any of this moving about thing. I used to keep a long novel in the car, because if he settled for his nap in the car seat, he would sleep for two hours, unless
I tried to move him, in which case the rest of the nap wouldn't happen today. Younger Chick made it plain early on that he was regimented in the matters of meals and sleep. Both had advantages, both had disadvantages. The main disadvantage was that they weren't the same and couldn't be treated the same.
I also agree that the presence of the child is a red herring. OP and DH received an invitation for 8 p.m. They refused it and explained why.
The invitation was reissued for 6:30, and they accepted it. It doesn't matter whether the reason for the refusal was that OP wanted to put her son to bed, or gets heartburn if she eats after 7:30, or had promised to be home at 9 to phone her mother, or has a religious objection to late nights, or had promised herself an all-night extravaganza of popcorn and Pride and Prejudice
on DVD. Joe and Annie knew that eating late was unacceptable to OP; they could have said 'oh, shame, we can't make that work, then. Joe can just come round at nine, and we'll get together for lunch or something another time.' As soon as they said that the meal could be at 6:30, knowing that it mattered to OP, they had an obligation to make that happen, no matter what they thought of it.