[gibbyhome]

I was wondering how many phones I can dev unlock to get the update and can I if they don't have the same live ID as me ?

[luk3ja]

I think they need the same Live ID, but all she has to do is register for the FREE windows phone app studio and then install the certificate recieved by email and then it will allow her to get GDR3 via the preview app

[eugie]

Can't install the certificate

[Jeric820PH]

I tapped the certificate but it didn't work too. But still gdr3 went ok with my 820

[Dustin Hodges]

A misconception is that you need app studio or a dev account. Its a bit of a big download for just one tool, but if you download VS2013 Express for Windows Phone, you can developer unlock your device. Just a month or so ago, MS made developer unlocking free to anyone (only with you being more limited on number of devices per account and the number of apps)

So you could do that, then install the Preview for Developers app.

To answer the OP, dev accounts get 10 device unlocks, while everyone else gets one, and non-devs can only sideload 2 uncertified apps. So if you're not a dev, you'll need to dev unlock her device with her own MS account.