sorry I don't know this. Maybe she should go shopping for new clothes 
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Natural looking undergarment
Katies-Mom-Melanie leotard
A leotard is tight, but with a darker and more messy pattern it will be harder to see what she hide.
A loose T-shirt over make it much better.
https://www.ebay.com/i/223661116931?rt=nc&_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3D0e29793148bd42119ec0cac45441ef22%26pid%3D100677%26rk%3D6%26rkt%3D30%26mehot%3Dnone%26sd%3D223607812814%26itm%3D223661116931%26pmt%3D0%26noa%3D1%26pg%3D2386202%26algv%3DDefaultOrganic%26brand%3DUnbranded&var=522739864305
These or the more expensive finer styles like Fancy Steel. The anal opening and ventalation are important for hygiene.
I'd advice to have your daughter stick to a skirt only style. It works the best with a belt
I will have to try this. My gym does not allow any pants or shorts. They only allow leotards. They don't want any clothing getting caught on the apparatus. Also some moves on beam require gripping with thighs, so fabric there makes it impossible as it would slip. (so shorts even if tight are out)
Zoey-and-Purity I'd advice to have your daughter stick to a skirt only style.
I agree with you, even without tighbands it is the best to hide the belt
- Edited
Laura I’ll see what I can and can’t hide. Boy friend goes to the same gym so I don’t think belt coming off is an option. We will see when they re open. Since covid I can’t go anyway. Which sucks. My tread mill has gotten way more use, but there is nothing that relieves stress the way flipping through the air does.
Katie my gym does not allow skirts or shorts. See last post
this was not directed at you, but a general observation
Katie My tread mill has gotten way more use, but there is nothing that relieves stress the way flipping through the air does.
maybe you can start your own little gym 
Katie Hence why I think she wont let me go to the gym without a belt
Maybe your mother would like to go with you