Monsieur Rioux, the best choice may be to just locate or create the recovery media and perform a fresh installation on the new drive. The media should boot and install to the new drive regardless of how it is formatted. Just tell it to use the entire disk. Then pop the old drive in a USB drive dock or USB case to recover any user data. Another option would be to back up any user data ahead of time. But then that's been done on a regular basis, right?
Right, she's exhausted another couple of options and is now ready to try the clean install later today.
With regards to "pop the old drive in a USB drive dock or USB case to recover any user data" - I've made back-ups before, without ever knowing how one might make use of it but hoping never to have to find out, but it looks like that's not an option now as she will want her games and other things back without doing it individually.
So the first question is once the clean install has been done, can the stuff on the old drive be transferred to the SSD via the same sata cable that was used for the failed migrate to SSD? USB dock/case sounds quite a different method. Or would it be better to back up onto an external drive instead.
Is that then just a case of selecting what to transfer to SSD - perhaps by only selecting what to copy from the HDD in the first place, before inserting the SSD? Any pitfalls?