Working with a union of structs in C

Say I have the following types:

typedef struct TYPEA
{
    int type;
    char[12] id;
} TYPEA;

typedef struct TYPEB
{
    int type;
    int value;
} TYPEB;

I want to use create a union of these types and 'int', so that I can access the "type" int without needing to know whether TYPEA or TYPEB is stored in the union (the value of int lets me determine which is actually stored there). I can't get the right syntax though.

My union:

typedef union MEMBER
{
    int type;
    struct TYPEA a;
    struct TYPEB b;
} MEMBER;

The union is accessed via:

typedef struct WRAPPER
{
    union MEMBER* member;
    struct WRAPPER* next;
} WRAPPER;

Questions:

1. (With 'w' as a pointer to an allocated WRAPPER struct) Accessing using w->member->a.id gives "request for member 'id' in something not a structure or union.
2. Can I assign a pointer to an already malloc'd TYPEA/B to w->member directly? Or does a union need to be malloced specially?

Thanks.