Unfortunately this miniature portrait is unsigned and the sitters are not known. However it is American and dates from around 1840.
The artist is uncertain at this point, but it should be possible to come up with an attribution at some stage from a comparison of styles.
American and indeed miniatures from all countries, with more than one sitter are very much in the minority, but it is interesting to compare this portrait with a random selection of some of the "mother and child" portraits from history. This shows what a timeless image it is.