You can transfer your attendee's funds from one signup to another. Transferring funds allows you to avoid extra payments and Stripe fees.
From the registration, click Issue refund.
Instead of refunding to the original payment method, refund to Other. Include a note about where you're applying the funds along with the new registration number, so it's easy to track down.
Apply New Payment
On the new registration for another signup, click Apply payment.
In the note, enter the signup the money is from as well as the registration number.
Don't forget to send the receipt to the Registration Contact, so they know the funds transfer has been made.
View the Transaction History
You can see the transactions on the Payments page.