I am looking for a point in the right direction on how to extend on the current invoice system, specifically on how it calculates price based on quantity.

Our business is in the Floor/Tile industry and products are usually sold per square feet.

qty = 1 would be 1sqft

However most tile is sold per box and not per square feet so I need to be able to check how many boxes a customer needs and adjust quantity and total to that number.

For example: A customer wants to purchase 20sqft of Tile

Each piece of Tile is 1.5sqft

Each box of Tile has 10 pieces in it, so a box of Tile is 15sqft

When I type in 20 as the quantity, I want to have the function check if a box of tile has enough sqft. If it does not, it needs to suggest purchasing 2 boxes for 30sqft and change the quantity variable to 30 and adjust the price accordingly.

I can program the functions, but I am completely out of my depth in regards to tying it into an exisiting framework such as odoo.

Thanks, any help or suggestion will be appreciated.