Answers
Does the Photos app work with Reunion 10?
Why can't I drag-and-drop images from the Photos app into Reunion 10?
Mac OS X version 10.10.3 (released April 8 2015) includes Apple's new Photos app, which is a spiffier version of iPhoto.
Unfortunately, the Photos app has broken the ability to drag-and-drop image thumbnails from the Photos app into Reunion. We are currently assessing the situation.
A simple workaround is to drag-and-drop images from the Photos app into your Reunion Pictures folder (or some other folder inside that folder) and then drag-and-drop images from that folder into Reunion 10 (for example, into the Media window or onto a person's button).
Important Note: When you open the new Photos app, you'll notice that it has created a new "Photos Library" (inside your user/Pictures folder). This does not delete your existing iPhoto Library (which is good). If you have records in your Reunion family file that are linked to images in iPhoto, then it's important to keep your iPhoto Library. i.e., do not trash your iPhoto Library after the Photos app gets installed with Mac OS X 10.10.3.