Manual conditions disappear

Hi

My client created sales with 2 manual conditions type ZCVF & ZXSD and created delivery. After creation of delivery client went to the sales order change mode and changed the incoterms Mumbai to Delhi and updated .After that manual condition types ZCVF & ZXSD is disappeared and system asking to maintain manual conditions type.

My client requirement is when he makes any changes in header level and updated ,manual condition types should not be disappear and system should not ask to maintain again.