Anonymous wrote:OP here. And her tourist visa was denied in 2018.
Mmmmh. I would take a pass. Too risky.
However, having a tourist visa denied as a young adult (late teen?) with very few binding ties and possibly limited money is not uncommon.
If she is from a VWP country and had a B2 denied I would chalk it up to stupidity (it's amazing difficult to receive a B visa if you are from a visa waiver country and eligible to travel under the visa waiver program... the problem is that nobody tells you that before you apply and even if you have the money and the binding ties if you don't have a good explenation why you need to stay longer than the 90 days you are eligible to be in the US under the VWP you will be denied, sibling in the US or not).
If she is not from a VWP country and had a B2 visa denied she may still be eligible for a J1. Just because she wasn't considered eligible for one doesn't necessarily mean she will not be able to get the other. However, if the risk the embassy saw was immigration intent she may well be denied her J1 which would leave you hanging without an AP at most likely last minute.