How can I use Xbox Live Arcade games and game DLC on my other account?

Ok, so I have two Xbox Live Accounts, and I have bought Xbox Live Arcade games and Guitar Hero songs with my old account. I was wondering how I would go about using all the things I bought with my old account on my new account (for achievements and whatnot)



I called up Xbox Customer Support and they assured me I could do it, but were unclear on HOW to do it...



Any help is much appreciated.How can I use Xbox Live Arcade games and game DLC on my other account?
I also asked the reps the same question, but what I understand is the following:



You cannot "combine" two Live Accounts (tags). I have some DLC on two different accounts and they told me that I can NOT combine the accounts or move any information across the two accounts.



I think it's up to Microsoft to fix this.