Adding Summarised fields - Help!

[Merit Solutions]

I have a report which sub totals fees for events. The report is generated weekly. Certain clients are also billed a weekly consultancy fee on top of the event fees. The amount of the consultancy fee is added on the client's record as it is always the same - week after week. I have sub summaries (sorted by client) displaying the totals of a client's fees for the week. I can also display in the sub summary, the weekly consultancy fee (if the client happens to be flagged as such). What I can not work out is how to total in a Grand Summary part, the total of these consultancy fees. I have attached a screenshot. (I need the total to read £600.00 and £105.00 in the example.) Any help is much appreciated.