Combined Analysis with Service Request, Activity and Claim

I have used Advanced Custom Objects to create a Combined Analysis Report. In this report I am displaying all Service Requests along with the associated Fault-Codes (re-purposed Claim object) logged on the Service Request and all Activities asscoiated with each Service Request.

Now I simply want to create a new report that lists the same information but filtered to only those records that have had the Service Request OR the Activity Modified withing the last 7 days. This snag I have is that when an Activity is modified only the modified date on the Activity is updated, even if it is linked to a Service Request and vice versa. So I have tried to create the report with a filter on the Modified date on the Activity but then I loose most of the other Service Request fields and the Fault Code in