Right now if Burn will start up MSI installer, it can fail with 1618 error message (Another installation is already in progress. Complete that installation before proceeding with this install.). It would be nice to have the option to indicate that msi installer (in bundle) must wait for other installations to complete.
It is a little bit related to https://sourceforge.net/p/wix/feature-requests/707/ , but in this case we would like to wait for other (not multiple instances of iself) MSI (Windows updates) installation to complete.
There was a discussion related to this process with proposed implementation: http://blogs.msdn.com/b/heaths/archive/2006/01/23/516454.aspx