Like Cocoa said, it can potentially ruin the initial bond of the brothers. Your girl has also lived alone for 2 years, so she could also be very territorial when meeting them for the first time. It’s a myth that they won’t want anything to do with you when they are all bonded. It honestly depends on their personalities. Yes, they will seek out their bun friends more than a human, but they will still go to you for attention too.
If you do decide to adopt, you need to be prepared for the worst case scenario of having three single bunnies. You’d need to let them settle in in a separate room away from the girl for at least a month.This will make sure their bond doesn’t break, and it will allow them to become familiar with you and their new environment. After one month, you can move them into the same room as her and start prebonding for at least a month, longer is better. Prebonding is swapping their items between their enclosures and swapping the bunnies themselves between enclosures. This helps every bun to get used to each others scents. After at least a month of this, you can begin short bonding sessions in neutral territory. Neutral territory is crucial because it allows every bunny to be on equal terms and no one can get overly aggressive and territorial.
Until they are bonded they will honest to God poop everywhere, so be prepared for that. They will turn into little poop machines that will want to mark everything, and that won’t stop until they are bonded. Aside from that, if you have the time (bonding can take months), energy, resources, and you’re prepared for any outcome, then I’d adopt.