I'd like to find a way to replace the last comma in a string with '&' or 'and'.

We send sales order communication to people other than the primary contact, and a list of those contacts is stored on each transaction in a custom multi-select field, which is sourced from a default list on the customer card.  This is kind of a clunky (I don't know scripting) set up, but it allows the sales reps the freedom to choose different contacts on a per-transaction basis, while also preserving the 'default' selection that the sales rep sets on the customer card so that they don't have to choose contacts every time they create a new order.  Having the contact