Update Fields based on Dropdown Box

I searched forum but can't find one that matches exactly my problem. I need to be able to have the fields in a the Customereply table update based on choosing a dropdown box. The drop down box chooses ClientID and looks up ClientID from the Customerrequest Table. Now I need the remaining fields to automatically update the Customerfirstname and the customerlastname and so on. The table that holds these fields is called Customerrepy. Do I need to add some code in Afteraddrecord events? Any help would be great. Thanks <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=8224&image=1&table=forumtopics' class='bbc_emoticon' alt=';)' />