Just a few questions:
What's the health and overall looks of the BPs?
What were they eating before?
Is your F/T warm enough?
Have you ensured the BPs aren't stressed?
Before you switch to live prey you can try a few tips.
1. Dip the prey in chicken broth then try offering to your BPs
2. Place under the hide (provided you are using a hide)
3. Place the prey inside and cover the enclosure with a towel (this always works for my BPs who refuse to eat).
4. Simple try feeding in enclosure (your BPs may just want to feed where they feel safe).