It might be helpful if you can post a link with the picture on.
Another painting called �Virgin and Child under an Apple Tree� by Lucas Crachan the Elder is another contender, but in religious iconography, cupid type children and apples feature a lot, so if you can post a jpeg somebody may well be able to identify the artist.
If you've got the picture saved somewhere on your PC, you can copy it into a hosting site to obtain a URL which can be posted here. PhotoBucket is a good one, I use it all the time.
You are quite right it is part of a larger picture. Sorry it took so long to find, but here we are prevented from accessing some sites, including ones with art on.
Anyway, the painting is called �The Three Children of Charles I� and was painted circa 1635 by Sir Anthony Van Dyke. The full work is shown here: