Auto fill consecutive row after processing from different sheet.

Hello excel experts,

I have problems with H2 from "Sell" sheet. I'm trying to get auto result in H2. IF the Coupon code in "Sell" sheet (C2:C32) have a match from any of (B2:B32) in "Buy" sheet, THEN it will calculate the value in "Sell" sheet G2, minus I2 in "Buy" sheet.
The problem is, I need to get the value based on the coupon code, and not depending from the same row on "Buy" sheet.

In "Cash balance" sheet, If there are any input in A2 from "Buy" sheet, it will input the same value (date) in A2. Also auto fill the C2 in "Cash balance"sheet with value from K2 in "Buy" sheet (the same row).
As for the B2 in "Cash balance" sheet, it will be looking up from I2 in "Sell" sheet, also fill out the A2 in "Cash balance" sheet from the same row in any of Value from A2 in the "Sell" sheet.
And the result will be in a consecutive row, based on the date.

I may be asking too much, but it's a great challenge if It was using only the excel formulas. I was googling for it and I know I may need to use the VBA or macros which is lacks of my ability.
So.. please help

Regards,
Peter