Is this a transaction in for review in the banking screen?So we can provide you with the best answer,is there a reason that you are looking to split it?Is it between sub accounts?
If you are looking to split a total payment (say £1000) between two card holders on the same account (e.g. £600 to Card-1 and £400 to Card-2, both with one BArclaycard account for instance), on the Banking feed it normally defaults to Transfer.
Change the type from Transfer to Expense in the drop down. You'll now get the Split option on the right, click that and you'll ge the option to align to different accounts. We have it set up so one card goes to one account named to the cardholder and one to another.
Select the names of those accounts in the Category drop downs and the respective split of pay-offs in the Amount fields to the right. This should pay off your individual Card accounts from your main Bank Account.