I see. The action on whose part do you mean? On the part of the ones agreeing or on the part of those who propose?Your sentences are close, but the sentence with "to" is more about an action than simple agreement. I also think that both would be just as good (and possibly better) without the second "will".
Agree to
1. To express that someone allows something to happen (We will agree to your proposal if you postpone action).
Agree With
2. To approve of a particular idea or action (We will agree with your proposal if you postpone action).