forward authentication, but take reply attributes from local db

[Vld]

Hello!

Lets say i have primary radius server with users in file. And i also
have secondary one, with the same users (logins and passwords are the
same). 
How do i forward/proxy access-request from primary to secondary and in
case it sends back access-accept to primary - it takes user attributes
from local database (of primary). No just return to NAS what secondary
gave me, but rewrite it according to local config.
The main goal of secondary - just either accept or reject user.

is it even possible?