The Eight of Wands indicates that there is enthusiasm and energy in this situation. There are opportunities that can be exploited. Your sister received something she didn't expect, which indicates that anything can happen.
The reversed Ace of Wands suggests taking a deeper look at the situation. Your sister may have had some signs that she overlooked or didn't notice. You might discover new opportunities if you take a closer look at the situation.
The reversed Six of Cups indicates that the end result may not be what you hoped for. This means that there are complications that need to be addressed before achieving a good result.
Based on the cards, the answer to the question is: No, not necessarily. While the situation is promising and full of energy, there is also the risk of encountering unexpected obstacles. So while your sister's gift could bring good luck to both of you, that doesn't necessarily mean it will. To get a more accurate answer it is necessary to take a closer look at the situation and the signs that have been overlooked.