1 Answer

I have two accounts. Can I merge them?

We don't currently offer a way to merge two accounts. Before you close any of your accounts:
Download the information you've added to the account you don't want to keep
Add the account you're keeping as an admin for any Groups or Pages you manage
Once you've moved all of your info onto a single account, please delete your duplicate account.

http://www.facebook.com/help/203498356357867/ 

Is it possible to merge two Yahoo! IDs?
ID: SLN3701Refers to: Yahoo! Account , Mail , Mail Classic , Mobile Mail

Description
This article describes how to combine two Yahoo! ID accounts using Yahoo! Mail Plus.

Resolution
It is not currently possible to combine two Yahoo! Mail accounts into one. You can achieve a similar result by upgrading the additional account to a Yahoo! Mail Plus account and setting it to automatically forward all incoming emails to a single account.
For example, if you have person_1@yahoo.com and person_2@yahoo.com as accounts. You could upgrade person_1@yahoo.com to a Yahoo! Mail Plus account. You could then set the upgraded account to automatically forward all received emails to person_2@yahoo.com, thus giving you only one account to retrieve all emails from.
Please visit the Yahoo! Mail Plus page for instructions on upgrading.
For instructions on forwarding your Yahoo! Mail Plus accounts to another Yahoo! email address, see the tutorial "Forward Yahoo! Mail Plus to Another Email Account".

http://help.yahoo.com/kb/index?page=content&y=PROD_ACCT&locale=en_US&id=SLN3701&impressions=true