Two main items (A+B) with one free item(C) how can we automatic determine in the Sales Order SD

[abulhasnat]

Hi Experts,

Out client requirement is if Customer Purchase two products like (A+B) having selling price with A= 5 PAC + B = 4 PAC then Customer will get one free product like C 100% free with C = 1 PAC. This should be done by automatic free goods determination. 

How can we achieve this? I have tried with SD BoM Explore and also Cross selling functions, in both way this requirement is not achieve. Standard free goods determination concept is 1:1 here client requirement is 2:1.

Example : Sales Order-X having three components A, B, C
Automatic Free Goods Determination is the requirement from the client side. 
Item A - 5 PAC - 100 Taka.
Item B- 4 PAC -  80 Taka. 
Item C- 1 PAC - 0 Taka.

Thanks & Best Regards
Abul Hasnat