Ability to set starting number for event

I have a very small viewing window in my backyard so I often take sequences on multiple nights. I'm sure other do this also. If I take four images the first night, I have Frame1, Frame2, Frame3, and Frame4. The next night I get Frame1-1,Frame2-1,Frame3-1, and Frame4-1. I'd rather get Frame5, Frame6, Frame7, and Frame8. Being able to set the starting number for an event count would be nice.