Hmmmm ,
1. Install Intellisync *address.mail.yahoo.com/?A=x&A2=11
2. Download the .csv file by selecting people only in your messenger list from *address.mail.yahoo.com/?A=B then upload it to other ID by signing in there
3. Use trillian . Open Trillian > Sign in with both the ID`s > right click each contact > select
add to then add it to other ID .