There isn't an elegant solution to this right now, unfortunately. We'd probably want to cancel/refund your head of operations' Gamma account/subscription. Then we'd add their email address to your existing workspace as a collaborator, but that will add an additional user charge to your subscription. If you want them to be in charge of the subscription we'd probably also want to cancel your subscription (we can prorate refund for an email change) and a new subscription would need to be made on the head of operations' email address.
It really depends on who do you want managing the billing subscription, which workspace you want to be the paid one, and how many active users you want in the workspace