If we’re splitting bills equally I’d recommend one of these two options:
Option A - Easier but requires a little juggling
Add all 6 people (2 couples (x2 = 4) + 2 singles) to the group and simply split expenses equally. You may also want to read about our Simplified Debts feature in our Knowledge Base and discuss it with your friends to see if it would help your group. When the trip is over you may end up with slight complications like A and B both owing money to F or A owing B money.
Simplified debts will help here as A could record a payment to B for the amount B owes to F. B would be settled up and A would owe A’s share and B’s share to F. With or without Simplified debts, A can record a payment to B in the group and they can figure out how the couple wants to balance it outside of the group.
Options B - Slightly harder but smaller surface area
Add only 4 people to the group by consolidating the couples to a single representative. For example A, C, E, and F would be added with A representing A and B’s debts and payments. When splitting expenses, instead of splitting them equally, split them by shares. Assign each couple's representative 2 shares and the single folk 1 share. For example when splitting a $60 expense, you’d assign 2 shares each to A and C and one share each to E and F. A and C will owe $20 ($10 each) and E and F will owe $10. The benefit of this approach is that it simplifies the couple confusion as couples will often pay as a unit but the downside is that it will take a little longer to enter each expense.