Is there a way to append/extend a MACRO value ? For example, I have a arbitrary number of includes, each of them declare a struct that need to be listed later

Is there a way to append/extend a MACRO value ? For example, I have a arbitrary number of includes, each of them declare a struct that need to be listed later on. #define MOD_LIST // start with an empty list #include "mod/a.c" // MOD_LIST is: a, #include "mod/b.c" // MOD_LIST is: a,b, Module modules[] = { MOD_LIST }