Just another question from another will - have you come across 'sonne' used to refer to grandson (year 1569)?
While I would never rule it out, I haven't seen an example myself.
The word
sonne could be used for:
1) A natural son born to the testator.
2) A son-in-law by reason of his marriage to a daughter of the testator.
3) A son-in-law by reason of being the natural son to a one-time spouse of the testator and another spouse of that spouse.
Does this help with your situation?