Sisters in Chinese / Japanese...

姉妹 is a Chinese, Japanese Kanji, and old Korean Hanja title for sisters.

Please note: It's kind of an uncommon title for a wall scroll.

姐妹關繫 is an expression that means “sisterhood.”

Literally, this means “sisters relationship.”

心の姉妹 is “heart of sisters,” “soul sisters,” or “sisters of the heart.”

This can be used for actual sisters to celebrate the heartfelt love they feel.

It can even be used by two women who feel a connection as if they are sisters.

This literally means forever sisters in Chinese.

This is a weird phrase in Chinese, as by default, sisters are forever. I added this because people were searching for it.

This literally means “sister flowers,” but it is really a way to say “soul sisters” like “soul mates.”

御兄弟 is a Japanese honorific title for brothers and sisters or siblings.

Please note: It's kind of an uncommon title for a wall scroll.

姐妹情 is one way to say “sisterhood.”

Literally, this means “sisters feeling, emotion, passion, or situation.”

婦女會 is an expression that means “sisterhood” as in a women's association, club, or group.

The first two characters mean “women.”

The last character means to assemble, to meet, to gather, to see, union, group, or association.

This Japanese term means “Sisterhood,” “Sisterly Love,” or “Sister Love.”

黑闇女 is a Buddhist title that means “dark sister,” “dark one,” or “dark woman.”

There are two sisters:
One is the deva, 功德女 (“merit” or “achieving”), who causes people to acquire wealth.
The other is the “dark one,” 黑闇女, which causes people to spend and waste.

These sisters always accompany each other.

手足情 is the love between siblings.

When you love, protect, care for, and have a deep bond that only brothers or sisters can.

The actual translation is “Hand and Foot,” but the relationship between brothers or sisters is like that of hands and feet. They belong together and complete the body. Even though this says “hand and foot,” it will always be read with the brotherly and sisterly love meaning in Chinese.

Note: During the past 20 years, the “One child policy” in China is slowly making this term obsolete.

妹 is the single character title for a younger sister.

In colloquial Japanese speech, this can be a way to say, darling, dear, honey, or my betrothed (only used when referring to a woman).

In Japanese, this can be the female given name Mai.

In Chinese, you will generally see this used in double form, “妹妹” or “mei mei” when referring to a younger sister.

兄姉 means “brother and sister,” in Japanese.

There's no perfect way to say it in calligraphy, but this is probably the best way.