I have recently read a version of the slaying of this Sovereign family. It mentions that Ephraim Searles was the uncle of Mary. I can understand that Ephraim may have been the uncle of Henry. (through the Eva connection to Frederick and Lavinia) I cant establish that Mary was of either a Searle or Sovereign by bloodline.
Possibly some information to establish Mary's credentials may help here.
I gather they lived on Con 5 1 or 2.? In the 51 Census I gather this is Windham?
Thanks Marg in Oz