Hi @w9gga
There are 2 ways to deal with this - either split the payment down from 1 payment into multiple (1 per client), or creating a holding account. If you have this situation often, I would suggest looking at the holding account option.
There’s more details on this here which may help.
There isn’t a way to do this at the moment, however there is a feature request open for this that you may wish to add your vote/comments to.
What you may want to do however is pay the CIS element off first and then the balance of the invoice would hopefully match up with the prepayment. There’s two guides available for CIS on QuickFile, which are:
I hope that helps, but please let me know if you have any further queries