Life doesn't always work out as we plan. Someone may make a post that doesn't work with what you want. What can you do? Complain? Ask them to edit their post? You adapt; find a way to do what you need to do, without having the need for another person to adjust an already made post. The following is some advise to players in dealing with this kind of situation:

Keep Calm - No one is a mind reader, and if you expect them to do that, you only end up looking like a jerk. Relax a bit before you make your response, just so your cooler head will prevail.

OOC - if you feel the need to you can use double brackets ((like so)) to speak as yourself, and not as your character. You can let a person know your plans. To avoid wasting a post on just OOC ((which is bad)) try and make a post to go along with it.

Restate - Working off their post, you can try to reexplain what it is you intend, while still talking about what they said as well, so as not to completely disregard anything they said. You can use the OOC/Restate cycle until you both each the desired compromise.

PM - Private messages work when you think it can't be solved with short OOC messages. Take the conversation off the public forum and into private chat to arrange things the way you both would like them to resolve.