Hi Charles,
Unfortunately I don't think it is doable then, as this statement is dependent on whether or not the conditional statement can be involved.

For more context, each mergefield is linked to a part of the database we use, such as sourcing whether or not the client has an attorney, and if yes, the charge will be £82, so on and so forth. The charges will then supposedly be added together if they appear as true. Can this work as an if statement? Or do I have to stick with a Formula.

I've not really gotten too far with this