I encourage you to do so. More good reviews will make it look worthwhile.
The more people who download Flash, the more people will become aware of the other books and possibly purchase them. So anything we can do to help Flash will theoretically help Bad Apple.
I put Flash and Flash of Light together in a boxed set/anthology and included The Missed Wish for added value. It's said anthologies are attractive. Okay. It did take a massive amount of time.