Arnel:
SPDisplayRelatedInfo is designed to show the related info directly below the dropdown. If you want to use those values to populate other fields, you'll need to write your own script in the completefunc (or write code to grab the values yourself) to do it.
Note that if you are in 2010 or 2013, you can just "pull" those values across in the lookup column settings; no script required.
M.
SPDisplayRelatedInfo is designed to show the related info directly below the dropdown. If you want to use those values to populate other fields, you'll need to write your own script in the completefunc (or write code to grab the values yourself) to do it.
Note that if you are in 2010 or 2013, you can just "pull" those values across in the lookup column settings; no script required.
M.