Can I sort concatenated text strings based on other values (using MCONCAT)?

[fr.ma.young]

I have scoured this forum for the answer, but this issue doesn't seem to have been addressed yet. Here's the deal. I am using a formula that searches through a separate sheet for all text strings that match up with a certain Billing ID and Date. On that separate sheet, each of the text strings is matched up with a number that represents its billing value.

The pink lettering in my sample table below is not actually in the table, but just added for your reference to reflect the billing value that exists in the separate sheet I mentioned above.

	A	B	C	D
1	Billing ID	Date	Total Hours for Date	Combined Billing Entries
2	70610	4-Nov-2012	3.00	Proposal to lender [valued at 0.5 hours]; Revisions to final set of documents [the other 2.5 hours]
3		5-Nov-2012	1.0	Evaluation of refinancing specifications
4	81092	11-Nov-2012	0.75	Presentation for firm management

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Here is the array formula I'm using to generate the content in Column D:

=SUBSTITUTE(MCONCAT(UNIQUEVALUES(IF('Full Ledger of Billing Entries'!$I$2:$I$1002=A6,(IF('Full Ledger of Billing Entries'!$A$2:$A$1002=E6,"; "&'Full Ledger of Billing Entries'!$E$2:$E$1002,"")),""),1)),"; ","",1)​

As you can see in the table above, the formula has sorted the text strings alphabetically. My question is: how do I sort those text strings based on the number of billing hours associated with each? In other words, how can I make them show up according to their billing value, in descending order?

Thank you in advance for any thoughts you care to share.