Is there a different way to do this then having a separate field for each potential split in the transaction? Or is this the way that this is done?

I think it's better to use two tables with one-to-many relation.
Parent table holds TransactionID, date and other common attributes and it is linked to client child table with fields like TransactionID, ClientID and Amount.

This way for each transaction in parent table you can write multiple corresponding records (with the same TransactionID) in child table each for every client which take part in the transaction.
VFP has built-in native support for one-to-many releations.
This way number of possible clients for single transaction is unlimited.