I am familiar with the spelling Mundling. I have over 70 different spellings found in various documents for the name Munnerlyn. In SC to this day even though it is spelled Munnerlyn, it is pronounced Munlin. Different regions pronounce it a little differently, some people add a “d”, “b”, or “ing” to the pronunciation. So the name winds up being spelled Mundlin, Munderling, Mumblin, etc.
The branch of Munnerlyns extending from Joseph Munnerlyn from North Carolina spelled their last name several different ways. Three different spellings seamed to have stuck after 1850s. Munlin, Mundling and Munnerlyn. This is where Isabel’s line comes from.

Isabel’s brother Thomas Jefferson Mundling spelled his name this way, and I have a picture of his Son’s tombstone (Alex Mundling) with the name spelled Mundling. I don’t know what became of Isabell’s other brothers with mother Martha Hendricks; Seaborn & Brandon, but both Isabell and TJ used the spelling Mundling. Their half siblings with mother Louisa Miller used the spelling Munlin. The half siblings I have were Mary Ann F., Joseph Franklin, James C., John L., and William H.

Joseph I think may have been killed during the Civil War, I have found no record of him after 1860 other than Civil War service. Mary married a John Wesley Dawkins and remained in Mississippi. James and William both went to Texas, Fannin Co. John became a Baptist minister and remained in Mississippi. I believe most of the Munlins in the Pontotoc Co., MS area descend from him.

I would be happy to share information with you.
I have information on the Munnerlyns going back into the early 1700s.