How to manage quantity and price component from charge item to invoice?

Do you know how to implement price component in the invoice?
What I do, it’s to copy all price components from charge item definition of my charge item and to put it in the invoice. But when I have a quantity in my charge item, what I suppose to do? For now, I put the quantity in the factor of the base price of the price component but I don’t know if it’s the right choice.

Another question, how works factor and amount? The amount is the result of the factor? Or the factor is applied to the amount we put?

Thank you in advance :slight_smile: