For a Belgian born before it was Belgium, when there are discrepancies in capitalization and spacing of a last-name prepositions in official documents, what's the best way to decide which spelling to use?
The concrete case I'm struggling with: I've found a source for Franciscus in the geboorteakte of his son, but while his grandson is "De Cat", he signed as "de Cat" and the scribe wrote "Decat". I think the proper thing to do is to put in his name as he signed it, especially considering he was born in 1820 when Belgium was part of The Netherlands, but would appreciate any input.