In Windows 8 it seems natural to me that each person in a family has their own Microsoft Account with which they log in.

If you pay for an app on the Windows Store, you can install that same app on several computers using the same Microsoft Account. Good.

However, if several persons, in this case my children, each have their own account on the same computer, they do not get access to apps bought on a sibling's account, even if the app has been installed on the same computer. Bad.

(Compare this to iOS where you are allowed have several iPhones with different iCloud-connected accounts but all using the same iTunes App Store account, which is perfect for a family where all can then use the same app which was bought just once)

Is there any way to share apps between Microsoft Accounts (e.g. members of the same family)?

Alternatively, is there a way to run apps that are installed on a computer when you are logged in with a Microsoft Account different than the one used when installing the app?