Pretty sure this cannot be done?
On my old email 1 address I bought loads of apps for my iphone. Then bought my ipad and changed email at that time and for some reason set up a new account with email 2. Now I find I have updates from email 1 account and email 2 account and I have to keep on logging in with both different id's to get old and new account updates. Anyway I can transfer all previous purchases all to email 2 account?