Data transfer between two macs

If data is your only concern, the easiest would be to use OS X Migration Assistant to transfer the User accounts. http://support.apple.com/HT5872 As long as you have enough free space on both machines, you can transfer your user account to your sister's machine, and vice versa. Afterwards, you can delete the old user accounts to free-up disk space: http://support.apple.com/kb/PH18890

However, is data your only concern? What about apps? What about cleaning the HDDs of both machines to be sure there's no vestige of the previous user present? An alternate approach would be to use Time Machine to backup both machines to external HDDs, then do a full wipe of the HDDs and restore from the backups (your sister's backup to your machine, and vice versa, of course). The procedure for "what to do before selling or giving away your Mac" is a good guide: http://support.apple.com/HT201065

Whatever you do, remember to de-authorize iTunes, sign out of iCloud and other services on both computers, as outlined in HT201065.

 

Hi,

see here : http://forums.macrumors.com/showthread.php?t=1769522