PLEASE IMPLEMENT THIS! "saving the type of unequal split" so it can easily be updated instead of having to re-enter from scratch.
I have all the same issues as Xand3r has commented. Unequal sharing with large groups for trip results in A LOT of editing of expenses and this is a nightmare with Splitwise. We sometimes end up using a spreadsheet before entering to splitwise because of this issue, death to the spreadsheet please!

I too would like to set the total number of shares first, and then have splitwise restrict the individual number of shares.
I like this because using shares as 'nights per person' does not work as listed in the example. That example has to be removed. It only works when you set a total number of shares and each one get's a specific part

Lack of this feature feels very annoying to me as well. Even more, I believe that a lot of people uses only equal split, because unequal is so difficult to maintain. And while equal split in most cases is "save and forget" thing, when you go for unequal split, this means you are taking this expense seriously and will want to revise or fine-tune it later.

We use splitwise to share expenses in a trip with group of 10-20 friends. We have a lot of expenses that ideally should be splitted in unequal shares. Typically this is required for Food, Drinks, Rent. Let's say we go to a supermartket and buy a lot of groceries for the whole group of people. First, we need to enter this expense quickly, to record the fact that someone spent a lot of money for all this stuff. Next, later, we can discuss and agree how we split the shares (we can put smaller share for a kid, or for a person who doesn't eat much, doesn't drink alcohol, etc.). Important thing here, is that these discussions and fine-tuning of shares are an iterative process. We agree on a share with one person, save it. Next, we need to align with other person, and save his/her share, and so on.
Also, at the end of the trip we usually revise all expenses. Could be that sharing concept have been changed during the trip, and we need to adjust older expenses. Or we may notice that forgot to include someone into the specific expense, or someone included by mistake. Actually, when opening an unequal shared expense, we cannot see which shares or percentages were entered - only exact amounts for each person. This makes revising a nightmare.

Because editing is so difficult, sometimes we have to forget this fine-tuning, and just do an equal split. Sometimes this feels unfair for some people, who wants an easy and transparent way to record and see his/her share.

I understand that this change may be difficult for you, because you do all the calculations on the frontend, and save exact amounts to the database. I'we worked with Splitwise API, and know that it doesn't provide any shares/percentages, meaning you do not have them in the backend. But I believe that you can start making this change gradually, by adding additional information to the data model (type of split, shares, percentages), and still keeping backward compatibility with old frontends and API. You can save BOTH split amounts and shares to the DB, and if any frontend app is not updated yet, it will just work as before.

I'm assuming that when storing a bill, you merely save the effective numbers that resulted from the split method and discard the actual method and its parameters. https://slopegame.onl/

Seems this is bug or missing implementation.

When I split a bill unequally with the percentage option and save it, it will convert the unequal amounts to absolute values. So whenever I edit this bill, the amounts stored will of course not add up to the changed value. So I have to manually calculate the percentage myself and enter them again in the changed bill...

For me this problem is also the most important problem to choose if I will be using splitwise again or not. We are a large group to go on a weekend, and it is never possible to know exactly who will stay 1 or 2 nights, who will eat, if the families bring all of their kids or one less, ... so many reasons to make changes to the division of the parts after you filled in at first time. I can imangine you suggest to fill in later when we know definitly, but then we have to keep everything on another way. Now we filled in all costs in advance (after we went shopping and got the bill of the house), so we only needed to make little changes on the amount of people who are there for meals and overnights. But that seemed to be not possible. For me this is an important lack.

This was a problem on our latest group trip. When I had to adjust the total bill, I had to figure out what what the initial share split. Eventually I learned to annotate the share split in the notes of the bill in case the bill needed further changes.

'Remembering' the share-split in the bill, would be a great feature.

This is not an idea but what seems like a small bug.

When dividing an expense in a group by shares (i.e. one person has 1 share, the other 3, etc.), the expense amount cannot be updated. In other words, when I try to update an expense which is divided by shares, I get the following error message:
"The following errors occurred:
- The total of everyone's owed shares ($XX.XX) is different than the total cost ($YY.YY)"

I hope this is clear :)

When I add unequal splits in the payment and when my friend changes it to equal splits, give an option to revert his changes back so that the old split comes into picture again..

It's just like giving undelete option whenever someone deletes a bill.. Give revert changes option just like you gave undelete option..

You don’t need to store this information. You can recompute it
On the fly when you do an edit?
This is what the human making the input has to do anyway

I just don't understand why this is still open for so long.

It is absolutely nothing to do with your data structure, I am 100% sure because it is to do with UI/UX fix. This fix would just need <100 lines of code. In the UI, while switch "split by.." tabs, first time user already split it by share, ok, so this UI needs to remember this, and when I switch tag to "split by amount", then the amount should be calculated based on the previous select on "split by shares", and same with "split by %.. and other options". That's it, no rocket science here. The very clear bug here is, the developer just resetting the "split by shares" to "1" by default whenever I switch to its tab, a blunt direct error!!

We travel with friends and their children. For general expenses (like a house) we will count each adult as a share and each kid as a half share. We will also count adults with a couch as a half share vs one with a bed. It's ok to break it out by person since we can add the kids who don't have email addresses now, but when it comes time to settle by family, we still have to add together the members of the family. it would be good if you could link the members and identify them as "x family" and then someone could settle the family. Also, when putting the shares in for an expense, when you go back in, it shows the amount and not the shares. If you click on the shares button it shows everyone as 1 share instead of what was entered (like .5). It makes you unsure that the shares were entered correctly.

For what it's worth, I agree that this is an annoyance. I am splitting a rental house based on how long each person is staying at the house. While planning, some people agree to 3 nights, but later change to 5 nights. When I edit the split, I have to re-enter all 14 people's shares just to make this one change.

Or, a husband wants to pay for his wife. Rather than updating her share to zero and his to add 3 more, I have found it simpler to stay in the "split unequally" view and zero out her bill and adjust his for the difference.

Maybe this use case will help you all see the value of this feature.

Basically i have found that the simplest way to split a bill with a percentage of service charge followed by a percentage discount is by adding the amount exactly as shares, with each share being 1 cent. Hence, it is likely that 4 numerals is needed as each persons share will be likely to be from 1000(i.e. $10) to 9999 ($99.99).

However as currently the app only shows 1 numeral, it is difficult to see the entire value added. Also, it would help if the number "1" share was not input by default, as it would mean i need to delete that number before adding the exact share amount i need

I hope it's not pointless to reply to this rather old ticket, but for what it's worth, I don't think that this requires you to change your existing data structures.

I assume that currently, you only store the effective values that resulted from the split method that was used when saving a bill and discard the actual method and its parameters.
What if you enhanced the edit dialog (purely in the frontend!) to compute the individual split method parameters from the stored effective values? Apart from the itemized bill, there should be a unique or at least a minimal solution for all available split methods.

The only issue I could think about is possible rounding errors, but that should be solvable, too.

I agree, I think in other words I would like to assign a particular split type to a friend. For example, my wife and I split everything based on a percentage. So every expense we enter we would want to split in the same manner (60/40, for example.) I'd like to be able to edit a friend (in this case my wife) and tell Splitwise that any expenses shared with her will default to a percentage with those values.