Email notification to maintain substitution in SBWP

HI Experts,

Requirement: email notification need to sent when user maintain substitution in SBWP transaction.

Problem:  I have implemented BADI-WF_SUBSTITUTE to trigger the email notification but BADI is not triggering the when user maintaining the substitute.

Please suggest me, Do we have any other badi for SBWP transaction for maintain substitution

Regards

Ramesh