yes! of course it's okay, if that's the way she feels best, then go for it. however if in public maybe she should have a skirt or something on.
Don't wear underwear.
make them wear "goodnight" pull up underwear and not let them wear big girl or boy underwear until it stops
Briefs
You should make a list of the pros and cons, plus why you want to wear girls underwear. As a 12 year old boy, you will need to make your mom understand why you do not want to wear boys underwear.
You could tell your dad you are a transsexual or you have a gender identity disorder. However, he may get angry or send you to therapy. This may not be worth being able to wear girls underwear.
plastic or absorbent underwear
For a 12-year-old boy, traditional boys' underwear such as briefs or boxers would be more suitable than girls' underwear styles like thongs, bikinis, or hipsters. It's important to consider comfort and appropriate fit for the child's age and gender.
Then congratulations, you're wearing rainbow underwear on New Years Eve. *Applause*.
No
Of course it is. In fact, a 14 year old should wear underwear or panties. They support the rear and also shape them up so they do not become rather, well, saggy. So, yes, it is very much okay for a 14 year old to wear underwear or panties.
If the 12-year-old is fine with it himself/herself, then yes. But be aware of the infections and deceises it might come with it. A 12-year-old should not be forced to not wear underwear, as most people feel more secure when wearing underwear. Do not take that secure feeling away.
Whatever he's comfortable in.