Dynamic Action - create Infotype with another date

Hi everybody!

Does anyone knows how to change BEGDA date for infotype according to probation period set in IT 0016?

I mean, when I hiring new employee I want to make new record in IT 0008 with date equal to IT 0000 + probation period (IT 0016) + 1 day.

So, I can make a record with new salary automatically.

In dynamic actions I am inserting two IT in hiring:

INS,0016,,,(P0000-BEGDA),(P0000-ENDDA)

and then

INS,0008,,,(P0000-BEGDA),(P0000-ENDDA) and here I need change P0000-BEGDA to another date (mentioned above).

Thank you for any help!

Cheers,

Kanat