change dial string with some BLF button push

My back end server requires one string for directed call pickup, and another string for picking up a parked call.

To pick up a ringing blf I can push the BLF key and it works, however for my call park's I need to have a different prefix used, or a way to set the whole string.

Is there a config to make pushing an automic BLF be different than pushing a normal blf?

by changing this  value I can make either by BLF or my park/pickup work

call.directedCallPickupString="*99"

What can I change to make both work?