obviously you do not understand how IPV6 works.
So the entire family are posting at the same time from the same computer?
(and yes I know that all devices give you the option of using IPV4 or IPV6, but that’s just to make it easier for the user, IPV6 is how the technology actually communicates)
For small to large (under 5000 PCs), networks IPV4 is all that’s needed (and for any MS certified employee that’s about all they could cope with).
Once you start going to the 10k plus range of PCs…
IPV6 was introduced because there’s not enough range to cope with the entire planet on multiple devices with a 0-255 x 4 address range.
IPV6 actually refines everything to a single device.
So you can differentiate between your sister using her phone and you using your laptop (you will both have the same IPV4 address but the IPV6 address will separate the two).