In case of making combined bets, it must be taken into account that those combined that are made with several bets of the same event, will be cancelled if any of the selections are declared void.
They are easily identifiable, since the bet ticket will show a set of bets with a single resulting odd (See point B.3.22 of the betting rules).
In the case of a combination that includes selections from different events, the combination will remain valid minus the payment of the cancelled selection or selections.
These are easily identifiable, since the bet ticket will show the odd for each selection separately.
Here you can see how a combined bet on the same event looks, versus one on different events: