Fifteen days after the Spring Equinox is Tomb Sweeping Day. This is usually the 4th or 5th of April on the Gregorian calendar.
The literal translation of 清明節 (qīng míng jié) is Clear Bright Festival, where 清 (qīng) means "clear" and 明 (míng) means "bright."
Tomb Sweeping Day was originally the last day of the Cold Food Festival 寒食節 (hán shí jié). During the Cold Food Festival, families cooked food to give to their ancestors. They could not eat the food, so it always went cold. Many people no longer go through the three-day preparation of the Cold Food Festival and simply celebrate Tomb Sweeping Day.
What happens on Tomb Sweeping Day? Families go visit the graves of their ancestors. Since many of the graves are in the mountains, it must be warm outside on Tomb Sweeping Day. The Chinese tend to the graves by pulling weeds and sweeping away debris. They honour their ancestors by offering food and tea. They also burn spirit money, which is paper money 紙錢 (zhǐ qián). Tomb Sweeping Day is another day to enjoy time with relatives. Since they are already going to the mountains, hiking is a popular family activity. Kites 風箏 (fēng zhēng) are always flown on Tomb Sweeping Day. They fill the sky with bright colours. The kites are usually shaped liked animals, such as butterflies, or have images of characters in Chinese operas. All in all, Tomb Sweeping Day allows the Chinese to pay their respects to their ancestors and further appreciate their families. They also get to enjoy early springtime weather.
I've decided to go with the most common way to acknowledge your family members. There are also formal versions for most of these. There may also be more than one informal version. It really depends on your family and what your particular relative prefers to be called. Scarlet's family also uses Taiwanese, so she had to look up some of these to double check. Family can get a little complicated (though I'm sure you already knew that!), which is why some people just use names.
Immediate Family
Grandparents
Paternal and maternal grandparents are different, so they have different titles.
Aunts and Uncles
For aunts and uncles, you have to see which one is related to your parent. On the paternal side, the age of your uncle also matters.
Cousins
And I'll end with cousins. It is similar to siblings, where you have to see whether your cousin is male or female and older or younger. In addition, you have to look at their last name.
Same Last Name
堂
(táng)
Different Last Name
表
(biǎo)
Examples:
Narcissa Black was older than Sirius Black, so Narcissa would be Sirius's 堂姐
Draco Malfoy was younger than Nymphadora Tonks, so Draco was Tonk's 表弟