Dynamically set approval based on SD ticket based on user selected option for specific catalog item

Hi We have SM 9.50 and upgraded to 9.51 I want SM should automatically assign Approval on SD/service catalog ticket based on location (user selection/option) which user selects while submitting ticket. For example, end user 'John' selected location say 'XYZ' from user selection while submitting service catalog item from ESS portal. And another end user 'Rhian' select location say 'ABC' from user selection while submitting service catalog item from ESS portal. Now the location 'XYZ' service request managed by SPOC say '123' and location 'ABC' service request managed by SPOC say '456' so John requests should goes to '123' approval and Rhian request should goes to '456' approval for particular catalog item. My Idea to achieve this: 1) I was trying to pass user selected Location value from svccartitem table to incident table custom field (say 'svcloc') through script but neither getting any error nor value is getting set via script. 2) If custom field 'svcloc' gets set on incident table when ticket getting raised, then was trying to set approver based on below condition under approval definition condition $svcloc in $L.file='XYZ' (assign approver as '123' under operator) If anyone has done similar kind of requirement then please suggest solution/steps/script by which they achived this requirement.