Photo credit: National Galleries of Scotland
I suggest that one of the sitters is Margaretha van Godewijk (1627-1677) - a pupil of Maes. She appears in several paintings by Maes. There is one other portrait of her on the RKD website
https://bit.ly/3wa7mET. Both were from Dordrecht. The sitter on the right could be Samuel van Hoogstraten (1627-1678). Like Maes, he was a pupil of Rembrandt. Again, Hoogstraten was also originally from Dordrecht. The same lady (Margaretha van Godewijk) may be seen in Hoogstraten's Perspective Box with View of a Dutch Interior in the National Gallery, London https://bit.ly/3gBCO8P.
Apologies, attachments omitted by mistake.
The Collection has commented: 'The only secure portrait of Margaretha van Godewijck, an engraving after a lost self-portrait of about 1677, does not show sufficient similarities with the woman in NG 1509 to justify the identification suggested below. I am not aware of portraits of her by Nicolaes Maes. According to the biographer Arnold Houbraken, she spent some time in Maes’s studio, but probably in the 1660s, that is after this was painted. Without further evidence, it seems wise to not change the title of for the time being.'
This woman seems to be a subject of many of Maes paintings. If not clearly Margaretha van Godewijck, is this model otherwise known?
This looks very much like a family group, meaning a married couple with their child. The two proposed sitters do not fit that.