Why put both challenges together? I found a lot of my photos have both elements. Some of these may be placed into one or the other but some a well into both challenges.
I think I will go with a theme within the challenge themes. I haven’t mentioned leading lines in the descriptions but I am sure you will pick those photos among the light and shadow ones.
Starting with sunsets which make great light and shadows
Staying with artificial light play and shadows
and just some sunlight used in different ways. For indoors