The situation could be expressed this way:
- Alice, Bob and Sam are a family
- They each of have a prefered playing device (you are Bob given you said the PC was yours, if in my below fiction example isn’t matching the real situation because your wife isn’t on Xbox but rather on PS5, then change the names to Alan and Sonya for example).
Alice loves her Xbox
Bob like his PC
Sam enjoys his PS5
Alice buys a D4 licence for her Xbox, and create a Battle.net account for it, named ax
Bob got a D4 licence for his PC, Bnet account is bp
Sam got D4 licence for PS5, Bnet account is s5
3 users, 3 machines, 3 licences, 3 accounts
Right now, every can play with each other, but nobody can play on another on someone’s else machine.
If Alice is willing to play on PC and/or PS5, she needs to attach her ax Bnet account to one or even two other licences (depending on will of playing on one other system or one both others) that’s +1 or +2 licences
If Bob also want similar flexibility, he’ll also have to buy +1 or +2 licences and bind them to his bp Bnet account
If Sam wishes to play on his parents devices, once again, that +1 or +2 licences, all bound to s5 Bnet account.
You wish full flexibility for the whole family? That’s 3 PC licences + 3 Xbox licences + 3 PS5 licences.
If every one of you is just willing to play on his main device and also one alternative, then it’s at least 6 licences, or potentitially more if two people pick the same alternatives (but if the whole family also wish being able to play all together at anytime, and not on his main device).
This is the only way doing it “legally” (following Blizzard’s rules regarding the use of personal and non sharable accounts).
Now for intellectual purpose, if you begin with account sharing in order to maintain the user’s flexibility playing on various devices at a lower cost (set aside of the above rule being broken), you also enter into several headache situations (I won’t take in account situations such as a couple split, or the boy leaving the house), in fact when you’re not playing D4 together on your main device, one willing to play WoW (on the PC) while Bob is willing to play D3/D4 on a console mean Bob can’t play using his bp account (so not using his Diablo character), given someone else is already logged onto that account for WoW, etc. In that “operative mode”, the Bnet accounts aren’t anymore attached to the persons, but rather to the devices (and aside of being against the rules, it limits the playing characters available for each one, and the possibility to play several characters together e.g. Bob can only play his sorc on the PC, he can only play “his” druid on the Xbox (using Alice’s ax account), and only “his” necro on the PS5 using Sam’s s5 account, etc.). Probably the best way to create frustration and conflicts!
Edit : In the above example, I forgot Sam also had a PC so everytime you read PS5 above, in fact it was his PC, and his bnet account was bound to PC not the PS5, in such case nobody can use the PS5, but Sam & Bob can play on each other’s PC’s without having to bother about legal ease (bp account can be used on Sam’s PC by Bob and s5 account can be used by Sam on Bob’s PC) that’s up to -2 PC licences required compared to above legal explanation (or no licences changes if Bob will never use Sam’s PC and Sam will never use Bob’s PC), but then you need to buy from one to 3 PS5 licences depending one who’s willing be allowed to play D4 on that device (considering Alice uses the Xbox mainly - if it was the opposite, again it’s just a math permutation which is neutral about the number of licences you need to acquire/or by whom it’s owned). I made a mistake focusing on your message #6 with trying to explain who to answer “yes” to the 3 login questions.
It’s clear that given both Bob & Sam own a PC, you start with at least 2 PC licences. If Alice is willing on any PC, she has to buy the 3rd PC licence. And now you add 1, 2 or 3 Xbox licences depending on who’s going to play on the Xbox, and likewise you buy 1, 2 or 3 PS5 licences depending on who’s willing to play on the PlayStation. Alice always uses her Bnet account (bound to 1, 2 or 3 licences depending on which devices she’s willing to play), Bob always uses his bp account no matter on which PC he plays (1 PC licence, plus another or two others depending one which console(s) he’s willing to be able playing), Sam’s situation is similar to Bob’s except he’s playing on his s5 account bound to PC and potentially also bound to PS5 and/or Xbox (+1 or +2 licences). Everyone uses the cross-platform feature linked to his own Bnet account.
What’s the age of David? 