Using Seeed_Arduino_mbedtls in a sketch

I'm trying to use Seeed_Arduino_mbedtls in my project. I added '#include "Seeed_mbedtls.h"', but as it only includes "mbedtls/md5.h", "mbedtls/md.h", "mbedtls/base64.h" and "mbedtls/sha256.h" and I want to use other/additional functionality I included "mbedtls/pk.h" additionally in my sketch.

To get it to compile using "mbedtls_pk_parse_key" I have to additionally add "#define MBEDTLS_PK_PARSE_C 1". So this "#define" seems to work. But I additionally add "#define MBEDTLS_PEM_PARSE_C 1", "#define MBEDTLS_RSA_C 1" and "#define MBEDTLS_BIGNUM_C 1" to my sketch, because I want to use this functionality, but these defines don't seem to have an effect. The code surrounded by "#if defined(MBEDTLS_PEM_PARSE_C)" in "mbedtls_pk_parse_key" isn't executed.

Can anyone please give me a hint, why the defines don't seem to have an effect? Thanks in advance.

I just read Visibility of #define between sketch and library - #2 by system. Is this the cause, that only header files of the lib "see" the defines I have in my sketch?