It's the concubines' birthdays, and the Imperial Household and the Kitchen will send the appropriate auspicious items and banquet spreads.
As per protocol, a concubine's banquet spread is only enough to feast on in her own palace.
Concubine Jiang took out her own silver, spending money to have the kitchen prepare more spreads in advance. She wanted to host a feast.
In the palace, whether you attend a banquet, and how much gift you prepare, all have their own etiquette.
Invitations from those lower in rank are to be attended based on one's mood, with gifts given at random.
Invitations from those higher in rank must be attended if you're able to walk, and the gift etiquette must be comprehensive, avoiding edible things and primarily offering fabrics and jewelry, occasionally paintings and calligraphy.
"Then I shall paint a Birthday Celebration Painting for Concubine Jiang."
