Here’s how you can rearrange and correct the sentences for clarity:

1. We have a tradition of holding a family reunion on the first day of Tet.
2. In some cultures, burning white candles is to chase away bad spirits.
3. Link's family buys peach blossoms at Tet.
4. People practice in order to honor their ancestors.
5. Every month, people usually go to Buddhist temples to pray for good luck.
6. Young people often hold a party with their grandparents and children to wish for longevity.

These sentences now express the ideas more clearly while maintaining correct grammar.