Hello,
I've contacted WHMCS support in order to help with our issue and they replied the following:
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WHMCS does use the details provided by the customer at the time they register, it will use the details specified under Setup > General Settings when not specified, however, generally, this is only for the likes of email registrar however.
You may be able to have a customisation created by someone on our Community that could achieve what you are trying to do, however out of the box there's not a way to achieve this
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Is there anybody who can assist, guys?
Thanks!