adding swipe down to delete to a template in listview

Question

Hi All

I've got a complex control I'd like to build, it is basically a splitting utility that allows you to split an amount of money into sub amounts and recategorise and do some other stuff to the newly created amount, please see attached image to get an idea. I've been thinking about the best way to approach the situation and at first I thought I would build a custom component but I've been thinking that perhaps it's not necessary to do so. I'd just like to hear back from some of you on what you think would be a good approach to this before I spend a lot of time going down the wrong route.

What I'm thinking now is that I have a flyout the contains a listview each listview template represents a splitted amount and the user can create or remove splits by tapping on the right or delete a split by pulling down on an template which would then delete it(similar to how one closes an application in windows 8)

The complexity arises in that when one split amount changes, this needs to reflect in the previous split template as well since you are essentially taking money from one split to another. So I was thinking that one way to approach this was to have the templates dispatch events when they are modified and then to do some math to figure out the new values and then to update the model (which the listview is binding to) and this would update all the views. 

So that's kind of the general direction I'm considering going in, does anyone see any fatal flaws in this approach?