issue with cart promotion "cheapest also buy one get one,,."

issue with cart promotion "cheapest also buy one get one,,."

I'm trying to configure three different cart rules on my site which is I understand all of them should work with the action of "The Cheapest, also for Buy 1 get 1 free"

1. first cart rule should give 70% off all items from category A ( Discount Qty Step 1)
2. second cart rule should provide 100% of every second item from category B ( Discount Qty Step 2)

Both of these called rules works fine and my issue is with the third rule:

3. this cart rule should be 70% off every second item not including items from category A and category B
But no matter what action I did I cannot make it work only on the second item and on, and unforthantly I get a discount on the first item I add, and of course if I have other items in the cart this discount is getting weird and not very clear

iv tried using for this rule all the actions amasty has on the ext' but could not get this work properly.
what the best action to get 70% off on every second item from certain categories only?