On Margaret's Death Registration, Francis is recorded in the 'If married, to whom" section.
The informant section is Frank - Husband. There is no mistaking the 'k' for 'cis'.
The original record is not available.
Other than this document, I have found no record (so far) for Francis with Frank as a name.
As well as recording Frank in the Notes/Source for Margaret's death, should I also list Frank as a nickname?