I have this line:

He crosses the room to where a line of unpacked moving boxes sits on the floor against the wall.

I originally had it as:

He crosses the room to where a line of unpacked moving boxes sit on the floor against the wall.

Grammatically the first is correct, to match line with sits, and quite rightly Word is trying to force my hand. But the second one reads much better to me. I am a rule follower with grammar but this one is testing my resolve lol. Thoughts?