How would you be able to differentiate between different people logging on from say the same household?

It depends on the system design, if already exists. Most systems including social media platforms like Facebook, Snapchat, X use credentials and as long as different people log in using different credentials, the problem is resolved instantly. The problem will remain however when the system refers to IP address or some sort that identify the users from the 'household'. If that's the case and it is critical to identify, I would suggest the change in the log in method. If that is hard to implement due to some technical reasons or the behaviors of the users, we can consider different interactions between each user and the system to distinguish. For example, if it is a social media account, there's a possibility the preference on media would be different and/or the people they interact with. What's also important is to consider why do we want to differentiate the users. That will determine whether the trade-off of having the revised system and not having the access to the data, which one is more preferred.

Users logging in from the same household would probably use different accounts that would help identify different users even if they are logging in from the same location. In case the users are logging in from the same location using the same account I would use the device to potentially differentiate the different users although this may cause false positives when some users have multiple devices.

As an example when using a netflix account at home, me, my wife and my two daughters share the same account and location. However if we use only the phones we can identify three different users watching very different content. It is worth mentioning this is just an approximation.