Point BSEG-FDTAG via FB70 BADI/User Exit/Substitution rule

Hello everyone, I need help.

I want to find a point in transaction fb70 where I can create an implementation for the planning date field (BSEG-FDTAG)

The function that populates the field (BSEG-FDTAG) is (PAYDAY_DETERMINATION)

I tried to find a rule that skips this validation, but I couldn't, my goal is to find a BADI, user EXIT or substitution rule before filling the BSEG-FDTAG to be able to create my implementation

Any assistance will be greatly appreciated!

Kind Regards

Albert