howto modify To URI

1. Brekeke Product Name and Version:3.x

2. Java version: openjdk 8

3. OS type and the version: ubuntu 16.04 + tomcat + nginxSSL frontend

4. UA (phone), gateway or other hardware/software involved: na

5. Your problem:
I want to modify the toURI copying the first two characters in the fromURI
example:
this is original
From URI To URI
sip:ab100@200.80.20.250 sip:200@200.80.20.250

I want to transform the To URI
sip:ab200@200.80.20.250

thanks

[Matching Pattern]
$request = ^INVITE
From = sip:(..).*@
To = sip:(.*)@

[Deploy Patterns]
To/uri/user = %1%2
$continue = true