Import from iPhoto 9.4.3 to Lightroom CC

Hello,

I'm in the midst of trying to combine two large iPhoto libraries and pull them both into Lightroom.

The iPhoto library version is 9.4.3.

This is for a user, not myself, and I need to make sure to preserve as much metadata as possible.

Here's my plan:

1.  Update both iPhoto library versions to 9.6.1

2.  Import each Library into a single Lightroom Classic library, using the iPhoto import plugin

3.  Import the Lightroom Classic library into Lightroom CC.

Is this the least error-prone method to do what I want to do?  If not, what is?

I'd consider importing into Photos then directly into Lightroom CC but I can only do that with a single library, not 2.

I'm also wondeirng how reliable the Lightroom Classic sync to CC functionality is, and if I should use that instead.

Any thoughts?