Friend I adore but has form for the odd bit of CF-ery. This is offset against overwhelming generosity of time and resources, hence she's still a dear friend. But a couple situations have been spectacular. One I can share here.
Years ago we took a summer holiday with her and her then partner - DH and I didn't have children yet but were going to start trying soon and knew that, all going well, we might not have a child free holiday for a looong time thereafter. Friend and her partner happily child free, no intention/plans in that regard and indeed that is how it has played out.
Plus I have an obligation to visit parents abroad and wasn't that good then about drawing boundaries around this to create time for just DH and me. Demanding job, the works.
All of this she knew well.
She invited another couple to join us on the holiday - they had a child. She didn't ask. The couple was a friend of her partner. She knew we 'loved kids' since we were planning some so couldn't see why we would mind about the child.
DH and I had many more friends with kids and already knew the score about how cheeky parents can be when there is a spare pair of hands about for babysitting. We were 100% not interested in doing this.
There was one point when I was drying my hair after a swim where my friend actually came down and said - can you come upstairs and look after X? By the time I was done with the beautification the problem had been solved by the child's parents (or my friend etc.) Hard no.
Thank God the parents were not cheeky.