Promotional modifier for every 10 +one additional product every 10 one item free

Hi,

I need to create one promotional Modifier, one item in recurring (for every 10 items) and must buy one more item in recurring (for every 10 items) then only one item free.

For example : customer buys a product A(10 nos.) and must have to buy Product B (10 nos.)  then Product C is free.

If Customer Buys product A(10 nos.) and Product B (9nos.) then it shoud not apply

Both Product A and B should work as Recurring (for Every 10s).even if one conditon fails modifier should not apply.

Thanks in Advance.

Logesh