Choose whether the sentence includes a defining or non-defining relative clause.
This is essential information. Without the relative clause, we would not know what the person did.
The main point is about her brother being an accountant. Where he lives is extra information, and so it is placed in commas.
The location of the house is just extra information.
The relative clause is identifying/defining which dress (the one in the window, not one elsewhere in the shop). Without this we do not know which dress is being referred to. So it's essential. 'That' also tells you it's a defining relative clause.
The main part is 'Anne is going to join us for dinner.' The relative clause is just some extra information. It's not defining a noun.
The clause is essential as it is needed to explain what happened in Paris i.e. the person grew up there. 'Paris is the city' does not make sense on it's own.
'that my friend was in' is identifying which play the speaker is referring to, so it's essential. The use of 'that' and the lack of a comma also tells you it's a defining relative clause.
'My employers haven't given me my holiday pay yet' makes sense on its own. The speaker is just giving extra information to say that s/he thinks it's unfair. It is also separated off with a comma.
'They are the children' does not mean anything on it's own. The relative clause is needed to identify what is relevant about those particular children.
The admiration for Kennedy is just extra information. The main message is explaining when he was assassinated. This can stand as a statement without having 'whom I really admire'.