Dynamically changing the line description of IU lines to the description of the original line

I am creating an interunit journal with two lines having different line BUs. When the journal is edited it will create IU lines for one account as specified in the setup.

We have a requirement where we want to copy down the line description to the respective interunit lines. For example, if for line 1 of the journal I am having ASSET account and the line descr is Asset. when journal edit runs we want it to copy down the line description to the respective IU line created.