I have a form in a web application where users may input bank operations. In this form, they have to put an amount, and they can, if they want to, split this amount into different "budgets". A budget split is defined by a code, and amount and a percentage. The problem is that I'm not quite fan of my current implementation of the split part of the form, and I'd like to hear what you guys think I may improve.
Here's the implementation:
(It's in french, but the labels don't really matter here)
How it works:
When the page is first displayed, there is only the first select list, containing the available budgets, and no lines under it. The user first have to select the first budget he wants to input a split for, then click on the "+" button. When he has selected the budgets, he has to input either the amount or the percentage of each split. When he inputs an amount, the corresponding percentage is calculated, and when he inputs the percentage, the amount is calculated. When there is only two lines that have not been filled, an input into one the four cases left will automatically calculate the three others. If on input make the total amount splitted to be superior to the operation's amount, the input is recalculated to match the operation's amount, and if a percentage makes the total percentage to be over 100%, the input is recalculated to make the total to be 100%
But I think that this functionment is not really intuitive, and that the automatic correction of the user's input may be a bad feature from their point of view.
Should I change the way my form works? Thank you, and sorry for my approximative use of the english language.