Whoever owned the left side of the piece with father and son must have known a figure was missing due to that adult sized female hand left dangling on the lower right edge of the composition. Yes, they had lots of geld, but those expensive clothes sure do look uncomfortable.
That’s an Elizabethan collar before the era of Queen Elizabeth.
painted by the Flemish master Cornelis de Vos in 1626..........
Elizabeth I
Queen of England and Ireland from 1558 to 1603
From the article:
That photograph showed the "elaborate" details of the missing woman's arm, seemingly not noticeable in the portrait's current state, which researchers said "cast fresh light on how grand and elegant" the original portrait must have been...
Apparently the part of the portrait with the arm had sustained some damage, but was only revealed by an archived photo.