Hi there,
Leah's parents were John and Mary "Millie" A. (Kyle) Carland. John's parents were Richard Carland (b. 1825) and Emeline/Emily H. Knickerbocker (b. 1831, Yates, Orleans, NY). They were married 15 Oct 1849 in Washtenaw, MI.
I haven't found much info for Richard other than the marriage record and his name on John's birth record so I can't help much more with him so far - I would guess that Richard was Michael's brother though. Emily is the daughter of Abraham and Lucretia (Warner) Knickerbocker. I haven't researched beyond Abraham, as it's not my line, but Lucretia's parents were Enos and Pricilla Elizabeth "Betsey" (Ellsworth) Warner. Emeline married George Warner sometime between 1849 and
I hope this helps! I have a private tree on Ancestry and if you wish to connect with me there, I'm happy to share what I have as long as you know it's a work in progress and not perfect.
Cheers,
Sarah