Chis,
After studing the situation a little bit more I found the way to do it. This is what I did in BizObj.first() method:

I reeplaced:

loDataAccess = This.GetDataAccessObject()
lnRetVal = loDataAccess.First()

with:

IF This.UseRemoteExecutant()
  tcExecString = "nav_first '" + SUBSTR(This.GetAlias(), 3) + "','" + ;
 		This.cDescField + "','" + This.cUniqueIDField + "'"
			
  lnRetVal = This.RemoteExecutantExecSQL(tcExecString, 'cSQLPassThrough')
	
  IF lnRetVal > 0
    SELECT cSQLPassThrough
    lcProperty = 'This.' + This.cUniqueIDField 
    IF TYPE('cSQLPassThrough.id') = 'N'
      &lcProperty = cSQLPassThrough.id
    ELSE
      &lcProperty = VAL(cSQLPassThrough.id)
    ENDIF 	
		
    USE 
		
    lnRetVal = This.Requery()
  ENDIF 

  RETURN lnRetVal
ELSE
  loDataAccess = This.GetDataAccessObject()
  lnRetVal = loDataAccess.First()
ENDIF 

The key is using the method RemoteExecutantExecSQL which I discover after studing the situation.

Thank,
Monique