How to use an older full backup set as a baseline

Hi,

I was wondering if its possible for BE2012 to use an older full backup set to run incrementals or differentials against. (maybe there is a way to delete the entry in the BEDB for the last full backup)

we do full backups monthly, weekly differentials and daily incrementals.

Our last full backup failed and from what I have been told, a timestamp is still entered into the BEDB for that backup definition so I believe our next differential will use the failed full backup as the baseline.

Anyway to get around this situation aside from doing the full backup again.

thanks in advance