Add the dinners, the cable cars and the taxis as they happen. tab-it adds it all up and shows who owes who.
↑ it's free, promise. open source too
Open the trip and it's there: €420, paid by you, split four ways. Two people paying one bill works too.
Both. Each currency keeps its own balance, so you owe what was actually spent.
One screen shows the total across everything you share. When they pay you back, tick it off.