I don't think it would matter because you can still order her phone on your Apple ID (I just did a fake test with the iPhone 8), when it comes to inputing a shipping address, you just enter her mailing address on that page. Just note that if through the carrier and you order it from Apple.com, it will pull the address from your carrier account so you can't change it then, you'll have to change the mailing address at your carrier account. However if it's the sim-free model, there shouldn't be an issue.