Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Could you elaborate on what you are trying to do, exactly?
It is possible to keep multiple accounts for different purposes and still have them share one and the same subscription. The account which pays for the subscription can invite other accounts to share, as you know. Sharing works if you have a Microsoft 365 Family (or 365 Premium) subscription.
You also mention a 365 Personal subscription, and it won't be possible to use it with an account that also has a Microsoft 365 Family subscription (if that is what you are trying to do).