you just do not link INFREC01 to COND_A as it is not necessary
you load your info records with INFREC01 and later you load COND_A
you do not even need to log somewhere the created Inforecord number.
COND_A automatically posts the condition to the info record based in the values given in the E1KOMG-VAKEY field .
you have to download your conditions from source system. I usually do this in SAP to SAP migration with SQVI. , joining KONH and KONP (minimum). Based on KONH condition table field you select either conditions for loading into A017, A018 or A025 table.
Based on that info you have to put your VAKEY field value together.