If WO relate to CH not any reason realte WO to SC, but if you are real like doing additional realtion to SC, so create 1-st DB Rule where you will update field in Related Changes field SourceID( or select another one) by SC;ID, second DB Rule for CH where if changed Source ID fields Update in All Related WorkOrder(s), 3-d DB Rule where Action "Update from External System": Output Sourceid, Input Servicecall;ID. For External Syste need write one Cgi or servlet(Tomcat) script where you will send SC ID and retur this ID, that very simple. How it need doing in sd45_sp8_addendum_eng.pdf
Hi WO1 in CH, WO2 in SC. Variants 1. if you like WO2 be a COPY of WO1 and SC not save it, so that not possible. 2. if you like WO2 be a COPY of WO1 and SC after save, that possible, if you are create script or class for creation WO2 as copy of WO1 with relation to SC.
3.not see any reason in 1.and 2 when WO1 possible reate to SC too.
byt somtime people like sent information from one case to other, but for it using one filed where store information about initiator or history of work. We use field "Information Update" what after every change store in "information" and This "Information" possible copy in any cases after creation of them.