1847 June 5, “Sketch of the Traditions of Germany”, inSharpe's London Magazine: A Journal of Entertainment and Instruction for General Reading, volume IV, number84, London: T. B. Sharpe, 15, Skinner Street,Snow Hill,→OCLC,page 83, column 2:
There was the wife of themännlein, dressed in a robe of silk, richer far than was ever worn by wife of burgomaster; and there were his brothers, and his daughter, with her fair hair falling over her shoulders, and her exquisitely soft blue eye.
1902 May, M. C. Gale, H. Gale, “Children's Vocabularies”, in J. McKeen Cattell, editor,The Popular Science Monthly, volume LXI, New York, N.Y.: The Science Press,→OCLC,page4950:
It is astonishing how this activity keeps up to the end of the day and how the child struggles against fatigue and sleepiness. After having looked at his Brownie book in bed awhile S. was laid down by his mother to be sung to sleep as usual and the gas was turned down. Whereat he said: "[…] right,—Yes. M., S. want those two pieces paper,—give S. some paper. 8. have to roll up. M. cover S. Where P.? Where P.? M., where P.? M. sing loud. M. lie down on P. bed," when theMännlein suddenly fell off to sleep.
He put his pistol under Hannibal's chin and patted him down. He kicked Hannibal's gun away. Grutas took a stiletto from his belt and poked the tip into Hannibal's legs. They did not move. "Shot in the spine, my littleMannlein," Grutas said.
The plural generally remains unchanged.Männleins is a rarer and possibly dated variant in the diminutive sense. (CompareFräulein, in which thes-plural is quite common.)