Billable Expense Line Items on Vendor Bills Across Multiple-Subsidiary Projects

Hello.

[FONT=Arial]I am running into an issue with [/FONT]Billable Vendor Bill Expenses for multiple projects (multiple subsidiaries):

The native functionality filters the Customer (Project) field to the projects associated with the subsidiary of the Vendor at the line level.  Which means that I cannot allocate multiple projects (projects belonging to different customers/subsidiaries).

Is there a way to get around this? Ultimately we would like to select any customer project at the line level, mark them billable, and invoice these billable expenses from Invoice Billable Customers menu per project.
 
  Have anyone encountered this issue before, and what would be the workaround?  Any suggestions/ideas would be greatly appreciated – very urgent and critical.