The Raiser's Edge and Blackbaud NetCommunity operate as an integrated system, and must be considered collectively. If a restore of The Raiser's Edge database is required, a restore of the Blackbaud NetCommunity database should also occur. These should be restored to the same point in time; i.e., if you restore to Monday morning's version of The Raiser's Edge, you also need to restore to Monday morning's version of Blackbaud NetCommunity.
Though there are many ways data could be corrupt by failing to restore both backups, but one example would be the processing of a new user sign-up request. If you have processed a request today and linked it to a record, but then restore to yesterday's backup of The Raiser's Edge; you will then have no link between The Raiser's Edge record and Blackbaud NetCommunity account.