Just some of the basics:
She was the daughter of Princess Louise of Denmark and thus the granddaughter of King Frederick VIII and Queen Louise (aka Aunt Swan). Her mother died while she was still a young girl officially of meningitis but there were rumors of suicide given that her marriage was an unhappy one. She had 2 siblings and 2 half-brothers by her father's 2nd marriage.
She was one of the string of Louise's going back to the famous Queen Louise of Prussia
her daughter Louise (1808-1870); who married Frederik of the Netherlands
her daughter Louise (1828-1871); who married Carl XV of Sweden
her daughter Louise (1851-1926); who married Frederick VIII of Denmark
her daughter Louise (1857-1906); who married Friedrich of Schaumburg-Lippe
her daughter Louise (1897-1938); who married Friedrich Sigismund of Prussia
her daughter Louise (1917-2009); who married Hans Reinhold (they later divorced)
Her brother was at one time engaged to Princess Irene of Greece but it was broken off.
Her husband was a renowned equestrian who died in a horseback-riding accident after a little more than a decade of marriage leaving ML with 2 small children. He was the nephew of Empress Augusta Victoria of Germany, the son of her sister Louise Sophie. The family often butted heads with the Imperial family.
Her daughter, another Louise, recently died, the last of the Louise Line.
The marriage was pretty low-key, occuring during WW1.
Princess Marie Luise, spouse of Prince Friedrich Sigismund, younger brother of Agra
And here she is with her daughter Luise in 1918