How to use BADI "CVI_CUSTOM_MAPPER" to prefix BP number?

We would like to use this BADI CVI_CUSTOM_MAPPER to prefix Business Partners.

For example, AR Customer number 223344 then BP number must be BP223344 for Collections.

We are using the MDS tool with CVI settings. Currently, this replication tool working fine (as well as tcode FLBPD1). However, if the AR customer number is 223344, then BP created for it is 223344 (which we do not want). We simply want to add prefix to this number as BP

Please share your recommendations and thoughts.

Thanks!