the girl in question sounds pretty relaxed and close to her aunt, so what better a person to allay her fears and educate her about the benefits of a mooncup? Wish someone had told me when I started to use one, years of icky tampons and towel use unecessary. And like you say, giving her one for her consideration and giving her the info isn't the same as forcing her to wear one.
"teens can use a Mooncup ? if a young teen I?d personally recommend Ladycup www.ladycup.eu as these are smaller and made from a softer silicone so may be easier for young teens to use, but Mooncup would be easy too.
Menstrual cups are very easy to use, the only issue really would be that to some people it?s a totally new concept so that may make it more difficult for them to get the hang of, but once you do it is second nature. As they are silicone they don?t cause friction when you try to insert them and they glide in more easily without getting stuck half way which can cause pain. You can wear a menstrual cup any time of the month (including to bed, for sports like swimming, during light-flow days, before your period is due) so you can actually try using one before your period is due to get the hang of it.
I think most teens are concerned at first about the size, but the vagina is made to accommodate much more than menstrual cups, the vaginal walls will stretch to allow for a menstrual cup the same way as it would for a tampon. FYI if you have problems with insertion first time, masturbation is best as this naturally relaxes muscles, the vagina becomes longer/wider and it lubricates itself, alternatively use lubrication like KY jelly or olive oil, menstrual cups can be used in bath or shower too which can make insertion for the first time easier. Menstrual cups really are not much bigger than tampons; there is a photo on this page comparing Mooncup (which is about middle sized compared with other menstrual cup brands) with a tampon - www.geocities.com/angua_nemi/inde?
They are easier for convenience too as they can be left in safely without leaking for up to 12 hours at a time, you rarely have to empty in public but when you do it is less hassle than with tampons or pads, you don?t have to carry spares or worry about running out, you don?t have to change sizes in accordance to flow, you can empty in the shower, they don?t cause menstrual cramps, you can get a clearer idea of your flow pattern, they last for up to 10 years so a lot cheaper than some other options, etc.
Obviously they are far better than tampons for teens, and for anyone, tampons prevent normal vaginal cleaning, give bacteria the perfect place to multiply, and commercial tampons contain chemicals, bleach and additives, thus why tampons are linked with so many health problems ranging from increased menstrual cramps to cervical cancer, vaginal infections to toxic shock syndrome. With teens these risks are increased due to immune systems not being as strong as in adults and walls of the vagina being more delicate so more prone to damage ? menstrual cups have no health risks associated with them what-so-ever so from a health and hygiene point-of-view they are far better for teens. Tampon health web site discussing various health issues concerning tampons - www.spotsite.org "