I have a daughter, she is 4. We all went to a fancy dress (costume) party for new year, i went as Katie. My daughter thought this was funny, but ok as everyone was dressing up in silly outfits. I'm not sure she is old enough to understand that i dress more often, nor do i think it would be fair for her to know something like that.
Regarding telling kids as far as school and friends is concerned, i think there is a greater possibility of girls and her freinds being supportive. With boys and their friends is completely different. I was always bullied and teased at school boys will pick up on anything to bully another boy on, one thing i was picked on about was my parents getting a divorce, so if it was widely known about a father crosddressing this could potentially be a living nightmare for a boy in school.
