I consulted with a Herald Buddy about Marschall (because everything else should be fine – Maria is well documented and SCA groups as locative bynames are cool) and found some things.
First of all “Marschall” has been registered before, so we have that documentation from the Online System of Commentary and Response:
<Marschall> – R&W, p. 300, lists a <John Marschal> in 1296 and a <Rainald le mareschal> in 1140. “Surnames in 15th Century York”, URL:http://heraldry.sca.org/heraldry/laurel/names/york15/surnames-alphabetical.htm, lists Mareshall and Marshall. “An Index to the 1296 Lay Subsidy Rolls for Rutland, England”, under the Bynames section, URL:http://heraldry.sca.org/heraldry/laurel/names/Rutland/bynamesalphabetically.htm, lists Mareschall. Based on these examples, we believe <Marschall> to be a reasonable spelling variant.
Unfortunately, this documents the name to Germany, not England, and German and English aren’t compatible languages.
Truth is, Maria Marschall of Seareach is totally documentable for England. I can find some Marschalls in Germany via FamilySearch, but they’re all super late period. Like, born-in-1599-late-period.
Recommendation from Herald-Buddy? register it as English and play German. 😉
(Herald Buddy blogs over here: [Link] You should go read it. <3)