Right now, If we wanted to add recurring booking credits to a clients account, they have to be charged directly for the credits.

This means:
We can't give free trials with recurring credits.
We can't allow a client to attend without paying through TZ because they may be getting free training or they are paying by other means.
We can't edit/cancel the payment or credits without also editing or canceling the payments.

I suggest simply removing the requirement for a recurring credit package to be paid for directly. We could still attach a payment to it if we'd like or take payments not directly attached to the credits.