Have a way to record an expense without adding it to the bill
Sometimes I want to record and show to the whole party how many times on, for example, a road trip, we got gas, but if that was all to be reimbursed to one person later by someone outside the party, have a way to not actually add it to the tally. This way everyone knows the total expenses, but know that it's not part of the actual bill.
While there isn’t an officially supported way for doing this on Splitwise at the moment, you can add a transaction in a group where you completely paid for something, and you are the only person who owes any money for it.
Lets say if you paid $100 for Gas, just add an expense titled ‘Gas’ and say that you paid $100, and untick everyone else except you from the ‘split equally between’ section and save the expense. This will achieve what you’re asking for: everyone will be able to see the expense and it will also count towards total group expenses, but will not count towards any individuals’ balances, including you.