These are two different records, so this will only happen 'automatically' if you include a mapping of each variable from the RITM to the change_request record at the time it is created. The method will depend on how you are creating Change Requests from RITMs, but can likely be covered by a before Insert Business Rule that runs on the change_request table. If the parent field is an ritm record, or however you're relating these two records in your case, do a GlideRecord to lookup the sc_req_item record, then a line of script for each ritm variable to change variable.
