The phrase 'agree where' is correct and usable in written English.
You can use 'agree where' when you want to refer to an area or point, or when you want to refer to a general idea. For example: "We all agree where the issue lies, but disagree on how to solve it."
Senator McCain, if you "agree," where is the proof?
They cannot even agree where most of the energy sits within the crumpled ball.
"But we shall discuss and agree where to sink the borehole," he said.
This is one case, many New Yorkers would agree, where butterflies should not be free.
The proposal foundered on two points, both sides agree: where they would live together and who would technically have custody.
Maybe it was, maybe it wasn't — years later, the two couldn't even agree where they'd gone that night.
Bureaucrats and enterprises negotiated the acquisition of inputs and agreed where the final product should go.
Yet instead of engaging as an equal partner in international forums, agreeing where he could, disagreeing where he couldn't, Putin has defined his relationships through antagonism.
The church has always promoted a distinction between the two spheres – temporal and spiritual, civic and religious – without ever, of course, agreeing where the border between them lies.
Everyone agreed where the ball hit, but the umpires said it qualified as a home run, even though the ball did not clear every portion of the wall, which the ground rules say it must to be considered a homer.
Looking for an alternate publication mechanism, Ellsberg returned to his idea of having a member of Congress read them, and chose Gravel based on the latter's efforts against the draft; Gravel agreed where previously others had not.
