Wouldn’t that depend on ESPN’s terms of service?
If one subscription is for only one person and the members of their household, yes, I would think that sharing that subscription information with those who do not meet those criteria would be to violate the copyright owner’s rights. A subscription is like a ticket to an event: each ticket is intended to be used in ways spelled out by the initial seller of the ticket, so long as they have a legitimate right to own whatever sort of content the ticket entitles a buyer to enjoy. One ticket usually can’t be used to get 19 people in the gate, and so it is with subscriptions. He who purchases has the right to view the content.
Would misuse of their terms of service in this way be sinful? I could see it being a venial sin, yes, although I’m not a moral theologian.
Willfully committing venial sin is something that should always be avoided.
Check ESPN’s terms of service. If they forbid what you are suggesting, then I would encourage you to not do it. If it’s not addressed, then find out some other way.