I always wore panties and it was normal for my kids to see me in panties. They never thought anything of it. One day I was dressed in skirt, stockings and blouse and my eldest came home unexpectedly. She was 8. Took no notice. Like it was no surprise.
After that I wore skirts and it was just normal to them.
After my wife died and I was a single Dad, I crossed dressed all the time. The eldest was 15 at that time. She helped me find nice stuff she thought I might look good in. Not typically behaviour of teens who die of embarrassment when their parents are being normal! But my kids were never typical.
Today they are all fine with it. But I never had to tell them to keep it a secret to the outside world. What happens at home stays there.