In preparation to remodel my bathroom I've taken down the drop ceiling in the kitchen. Romex for lighting is currently run through holes in the ceiling joists.

I found that the joists are only 2 x 6s, so I need to sister 2 x 8s to support the new floor above. (Total span is less than 10', so 2 x 8s are adequate.)

Since the cable will be well out of the way, with no chance of getting snagged or stepped on, can I secure it to the bottom of the joists or do I have to drill new holes and run it through those?