How do you prepare yourself if you are expecting twins?

i have a little cousin called nicole, who is four years old. she is a very spoiled little girl, who always gets upset when she doesn`t get her own way. she was an only child raised by her single mother. aunt rose had recently got married again. her husband is a man called harry, who was a single father. he has a six-year-old daughter called jade. jade had also been greatly spoiled by her father, who doted on her. after the wedding, the two girls did not get along. nicole often tattled on jade and got her into trouble. jade thought nicole was an annoying little sister. unfortunately, jade got cancer and was in the hospital for ages. she had to undergo many treatments, including chemotherapy, which made all her curly hair fall out. when she got home, people gave her most of the attention. they let her have her own way because of her illness, which made nicole jealous and bitter. nicole feels ignored and left out. she threw temper tantrums and became greatly attention-seeking. she had even tried to fight with jade on some occasion.. there were times when she was mean to her sister. nicole had teased jade, called her names and took her anger out on her. when they go out as a family, jade might not feel well and they have to hurry her home. nicole would cry and scream because she wants to stay and play. aunt rose and uncle harry would just comfort her, saying"we have to go home now because your sister is tired. we will play later." also, aunt rose is now pregnant and there are a pair of identical twin girls on the way. their names will be grace and emma. what can i do to help them?