How to Include Custom AVP in Diameter AA Request

Hi Team

I would like to use the user part of the SIP To or P-Called-Party-ID Header to use in the DIAMETER AA Request (by default SBC takes value from RURI).
One idea that came to me was to either include an AVP that by default have a value taken from SIP To / P-Called-Party-ID Header or insert a custom AVP have this value in the Diameter AAR. Once done, I could then write a Diameter-Manipulation that takes this value and use it on the AVP 444.

Please is there any AVP that by default have a value taken from SIP To / P-Called-Party-ID Header? If not, how can I insert a custom AVP that takes these values?