The parameter for 'list of sectors with which a sector may be combined' is embedded code and is limited to a maximum of 40 characters in a comma-separated list.
As an example, therefore, HH,KH,XH,UH,UN,UB,KN,YB,HN,UE,XE,KE,HE for LFEE airspace would 13 collapsed plus the elementary sector.
As this is embedded code that we have no immediate rights to, this is not a parameter that can be altered. The maximum is 40 characters.