Dopo tante ricerche, finalmente ho trovato la soluzione! Mi servivano due forum Mybb  sullo stesso dominio..il problema non era spostare i topic o altro..ma sincronizzare i nuovi utenti.

Ti traduco dall”inglese come fare! 🙂

1. Scarichiamo l’ultima versione di SQLyog Job Agent (SJA) per Linux
   http://code.google.com/p/sqlyog/downloads/list
2. Guarda il file esempio “SJA-sample2.php“
3. Modifica con i tuoi dati
   

   <tunnelinfo type="http">
   <url>http://www.yourdomain.com/SQLyogTunnel.php</ url>
   </tunnelinfo>

Modificare anche la parte relativa ai database
<tables all="no">
<table>
<name>`columns_priv`</name>
<columns all="yes" />
</table>
<table>
<name>`db`</name>
<columns all="no">
<column>`Host`</column>
<column>`Db`</column>
<column>`User`</column>
</columns>
</table>
<table>
<name>`host`</name>
<columns all="yes" />
<sqlwhere>host like '%%'</sqlwhere></table>
</tables>

Cambia per esempio (inserisci il ome della tabella che ti interessa in questo caso “mybb_user”

<tables all="no">
<table>
<name>`mybb_users`</name>
<columns all='no'>
<column>language</column>
<column>longlastip</column>
<column>longregip</column>
<column>lastip</column>
<column>regip</column>
<column>referrer</column>
<column>awayreason</column>
<column>returndate</column>
<column>awaydate</column>
<column>away</column>
<column>ignorelist</column>
<column>buddylist</column>
<column>dst</column>
<column>timezone</column>
<column>timeformat</column>
<column>dateformat</column>
<column>showavatars</column>
<column>showsigs</column>
<column>remember</column>
<column>hideemail</column>
<column>birthdayprivacy</column>
<column>birthday</column>
<column>msn</column>
<column>yahoo</column>
<column>aim</column>
<column>icq</column>
<column>website</column>
<column>regdate</column>
<column>usertitle</column>
<column>displaygroup</column>
<column>additionalgroups</column>
<column>usergroup</column>
<column>avatardimensions</column>
<column>avatar</column>
<column>email</column>
<column>salt</column>
<column>password</column>
<column>username</column>
<column>uid</column>
</columns>
</table>
</tables>

4. Per gli avatar sincronizza  (. / Upload / avatars /)

Cron Job
10,30,50 * * * * "/ var / scripts / SJA / SJA" "/ var / scripts / SJA /"> mydomain.com.xml / dev / null 2> & 1