My inbox has 1500 items in to process?

Is there a way to file each into its appropriate group instead of into its project?

At present, the window lets me drag one or more selected inbox items to one of my newly defined databases, but I would rather drag it directly to one of the groups belonging to each database, (each of my databases has a number of groups underneath it).
Am I missing something?

Tools > Show Groups & Tags

But when I do as you suggested, I can only do so when my project is highlighted. When I highlight the general inbox, I cannot make the “show groups” selection.

I think this is what BLUEFROG is referring to:
View>Show Groups and Tags:

You will be presented with this HUD window:

You can see that I have two open databases. I only have the contents of one database visible, but you can click the disclosure triangle and show the contents of the other. I can drag files from anywhere in DEVONthink to any location in any open database using this window.

Yep - that’s exactly what I was referring to…