Two things here : the use of 'vous' and the choice of tense.
Taking the last thing first, there are a few possibilities, depending on context. Both of your sentences are in the present indicative form. There is no way of knowing in French without more context whether this would translate back into English in the present coninuous (or progressive) form or the present simple. The coninuous form could be use in your example if you were describing an action which was taking place, that you were commenting or observing a scene.
Present Continuous :
Are you having/eating/taking your breakfast together?
Are you and your family having/eating/takign your breakfast together?
If however, you were intending to talk about a habits, regular occurence, then you have to use the present simple, which gives :
Present simple :
Do you have/eat/take your breakfast together?
Do you and your family have/eat/take your breakfast together?
Four possibilities then depending on quite how you wish to use the French you have cited in reference.
Second point. The use of 'vous'.
'Tu' is always used where your subject (the person doing the action) is singular and is the familiar word for 'you'. You have no choice about that, that's the way it is.
Likewise, if your subject is plural and the context requires a sign of respect, then you should use the 'vous' form. Further, if your subject is plural, then you have no choice but to use 'vous'.
In the second sentence provided in your example, the subject is plural. They comprise 'tu', (the individual to whom you are speaking) and the rest of his/her family (ils (they), them (eux)). Therefore the total number of people involved in the same action is plural, even if in that group you include 'tu', the group still contains two or more individuals, thus you ahve quite correctly put your verb in the 'vous' form with the '-ez' ending.
NB - I have taken the "ou" in your extract to mean "or" and not "où" with the grave accent, in which case you are considering 'where' the event is taking place. I have not dealt with theius possibility in my answer.