I think you can use ‘importnetlist’ to update just the compound part, namely just the sub-circuit of a whole configuration. In this case, you need to provide the name of the compound and make sure the netlist only contains the subckt part but not the MAIN CELL part otherwise IC will complain about the hierarchy.
The whole circuit should be imported once to include all the analyzers and connections, then update the sub-circuit won’t break any of the connections. An easy way of doing this is to put the sub-circuit in a separate netlist file and then include this file in the circuit (main) netlist file. Then you only need to import the circuit netlist once and import and update the sub-circuit afterwards.
I hope this could help let me know if you could not implement this.