I may crack a nut with a sledgehammer but me and my girlfriend have different accounts for different purposes and currencies. Since our main bank doesn't allow us to use a sub account mutuality by issuing a second ATM card we use multiple cards/accounts depending on country and purposes.

I would love to simplify this but is currently not a realistic option.
That why I started to put all payments (recorded money transfers / debits) in an excel spreadsheet what tells us who owns whom how much in regard of e.g. cost of flat, daily expenses etc. It is somehow similar to the spreadsheet available for download on Money Under 30 but bit more complex (with e.g. uneven shared expenses)

Now I reached a point where too much data got accumulated, so I would like to know if this app can work with shared expenses/liabilities and list who owns whom how much.

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I did some research on the web and found a plenty of free (open source) accounting software and shared expensed smartphone apps. The apps are too simple and mainly don’t allow importing data. So I need something in between. So far I found the following apps:

1. expensure.com
2. My finances
3. Settle Up
4. Splitwise
5. Tricount
6. WeSplit.it - Share Bills and Expenses

Since they don’t satisfy my need I read through some comparison website. These sites explain already a lot but nothing about shared expenses. They are:

1. Capterra Finance Software Blog - Top Free Accounting Software Options/
2. opensource.com - 3 open source personal finance tools for Linux
3. techradar - The best free accounting software 2017

So I ended up with a plenty of software packages which are listed below. May someone else faced once the same challenge as me and uses one of them. That would save me a lot of time of evaluation.

1. AdminSoft Accounts
2. AFAS Personal Plus
3. Apache OpenOffice
4. Banana Accounting
5. Buxfer: Easy Online Money Management
6. GnuCash
7. HomeBank
8. Invoice Expert
9. KMyMoney
10. LedgerSMB
11. moneytrackin'
12. Money Manager Ex
13. NCH Express Invoice
14. osFinancials Accounting Software
15. QuickFile
16. SlickPie
17. TurboCASH
18. VT Cash Book
19. Wave Accounting
20. webzash
21. xTuple PostBooks
22. ZipBooks

Hi @packelend, i would to like to add https://www.invoicera.com/ - best invoicing and billing softwaare in the above list.

What you're looking for may be found in a business-style accounting program; one that supports double-entry, accounts payable/receivable, billing, etc... This will certainly deal with the complex nature of your arrangement but may mean you'll give up functions typically found only in personal finance apps; simple budgets, phone apps, checkbook-style ledgers.

I've tried two of the apps on your list. KMyMoney was my pick for personal finance and have been happily using it for years. GnuMoney would seem much more in line with what you need. There may be a way to use a personal finance program, but it would take some creativity. I've got an idea on how to use 'brokerage' accounts and scheduled transactions to track the splits, but that would take some time to test out.

Good look on your search! Let us know how it turns out.

Thanks for the last one. It came in handy for my small business.