I have a copy of the Wasserliesch Family Register, which is a summarized transcript of Church Registers from about 1750 through early 20th C.
It lists several Matthias Mergener families. I think the most likely match to your Matthias is either
Matthias b 1816, m 1839 to Barbara Kohn (1813-1850), m 1851 to Elisabeth Kronenbusch, with children Matthias (b 1840), Nikolaus (b 1841), Maria (b1843), Anna Maria (b 1845), Matthis (b 1848), Johann Peter (b 1850), and Johann (b 1852).
Matthias b in Ensch, m 1844 to Maria Bach (b 1815), no children listed. (The lack of children implies the couple didn't live in Wasserliesch long after their marriage.)
There is a bit more information available that I can provide. If you want, contact me directly at tgkohn_at_aol_dot_com.