@User also consider using a

.include

directive that tells ngspice to load the needed magic subcircuits. In this case you just need to define the symbol

type

attribute to

primitive

(

type=primitive

). When creating the netlist xschem just generates the subcircuit lines (

Xxxxx node_list...  subckt_name

) and does not try to descend into the symbols. This is probably the most straightforward method, although it is not self-contained, it depends on some external file.