After serving their Mecklenburg lords for generations, a branch of the v. Schwan family turned up in Pomerania using a coat of arms almost identical (to my untrained eye) to the coat of arms of Mecklenburg. The v. Schwan and the noble Svan family in Denmark and Sweden were the same family, if DNA is to be believed, and the first v. Schwan must have arrived around 1185 at the beginning of the Danish hegemony of King Knut 6. Members of the next generation(s) of the v. Schwans appear to have been trusted members of the courts of the lords of Mecklenburg.
Why would a foreigner become so close to the Mecklenburg rulers?
Why would the v. Schwan family give up their iconic swan coat of arms and take the Mecklenburg coat of arms of their sovereign?