The coupon policy at Target does not restrict using a coupon on an item made free by a promotion, but keep in mind your store may refuse to accept it.
Buy 12 Smart Ones Frozen Entrees $1.89, sale price through 8/3
Buy 5 Get One Free through 8/3
Use one $5.00/12 – Weight Watchers Smart One Frozen Products – (heinzoffer.com)
Or $4.00/10 – Weight Watchers Smart One Frozen Products – (eatyourbest.com)
And use one $3.00/10 – Weight Watchers Smart Ones Frozen Food Items, limit one coupon or offer per guest, Target Coupon – (target.com)
And use one $1.00/1 Any Frozen Item, $1.00 or higher, Target Mobile Coupon (exp 8/31) Text FRESH to 827438
Final Price: $0.72 each, when you buy 12