Sometimes what you're thinking of as one transaction is really a series of steps that you would need to enter into BandHelper as multiple transactions.
In your scenario, let's say you get paid $100 for a gig and you want to pay a sixth of that to each of five band members, with the final sixth going into a fund. First, you enter the payment you received:
Type = Income
Amount = 100
Received By = you
Shared By = the five band members who played the gig
Then log the payments to each band member as distributions. In this case, each band member is due $16.67, but it's usually not worth taking the time to pay out exact amounts like that. If you pay them $15 or $17 or $20 each, BandHelper will carry the difference forward to the next distribution. So the easiest way to do this is go to the Finance > Totals page and click the Distribute button for each user who is owed a balance. This will open a transaction pre-filled with the following info:
Type = Distribution
Amount = current balance owed - you can then change this to a round number that you can easily pay out in cash
Paid By = you
Received By = one of your five band members
Then you can transfer the remaining sixth to your fund:
Type = Deposit
Amount = 16.67
Paid By = you
Deposited To = fund name
Shared By = the five band members who played the gig
Alternatively, if you simply want to put the entire fee into the fund, you only need one transaction:
Type = Income
Amount = 100
Deposited To = fund name
Shared By = the five band members who played the gig
Then if you want to pay the band members from the fund later, you can enter transactions like this:
Type = Withdrawal
Amount = amount given to each band member
Received By = this band member
Withdrawn From = fund name
Shared By = this band member
However, unless your fund is tracking a literal bank account, or tracking savings toward a large future purchase, I would skip the steps related to the fund. Your bandmates' money will simply appear as part of your personal balance until you pay it to them with Distribution transactions. So if your goal is simply to pay out to your bandmates less often, you could do the first step above after every gig, and the second step every few gigs, and you won't need the other steps.
Finally, when adding a transaction, look for the Defaults button at the top of the page. That will pre-fill the name, date and users from the most recent event. This saves a lot of data entry when you are logging multiple transactions, as long as you log them after each event.