fill a custom field on IM that was filled in SD


i have created a custom field (text character) on SD form. i want when escalate this SD into IM, to have the same field and its content. what shall i do?

example: on SD, a field called COMMENT as varchar(60). 

on IM, i shall create teh same field as varchar(60) but how can i bring the text that was written on SD into this field in IM form?