Change your settle up algorithm
When simplify debts is on and I click settle up and then pay with paypal, it tells me to make multiple small payments to those who are owed instead of one full payment to the person owed the most. For example, three people were owed money in my group: #1 was owed $400, #2 was owed $700, and #3 was owed $40. I owed $130 or something like that. Splitwise told me to may ~$20 to #3, then split payments to #1 and #2 as well. With the goal of minimizing total number of payments and paying back the person who is owed the most first, I should have been instructed to pay the full $130 to person #2.
With simplify debts on, it should work more like you expect in a group.
Marshall