how to move time machine from an old macbook a newer one using an apple time capsule on wifi

Here you go: Erase an AirPort Time Capsule in AirPort Utility on Mac - Apple Support

Not that it matters now, but if you were to populate the new Mac from the earlier one's Time Machine backup instead of one Mac directly to another, Time Machine would have picked up where it left off. Its existing backups (to the extent possible) would have been retained. You can still do that, if you so choose, until such time you erase the Time Capsule.

Another thought, while we are on the subject: you can also connect an external USB hard disk drive to the Time Capsule's USB port, and add it to Time Machine. That way, you will be assured of more than just one backup.

You can add as many additional USB hard disk drives to it as you wish, but more than one will require a powered USB hub due to the power limitations of the TC's USB port.

In any case you don't need to connect a HDD directly to her Mac. Time Machine continues to create "local snapshots" (fully restorable complete system backups) on the portable Mac and writes them to the TC whenever it can.