Neither an incident light reading in the open or one in the shade was going to give you the best exposure for a subject in the shade while also successfully capturing the overall scene. A reading taken in the open would have probably given you the best overall reading but the children would have needed brightening up considerably. If you had used the reading taken in the open and then given it about an extra two stops of exposure you may have retained some detail in the sky while not needing to brighten "dodge" the area in the shade as much.
The other option you could try in a similar situation is to take a reading in the open, another in the shade and set the exposure roughly in the middle. You would still need to adjust the brightness curves (or shadow highlight control) or dodge to get a suitable outcome. We cannot give you an absolute answer as it will depend on the dynamic range of the scene, the dynamic range of your camera at the ISO being used, the software available, your skill level and your preferred outcome or compromise.
P.S. Do you have any editing software available? The shadow highlight adjustments available in a number of editors is the simplest way to achieve a limited but often acceptable correction to the problem you had provided the exposure is reasonable.