Everyone gets really frustrated when all of theirs are not listed in the last will and testament of an ancestor. This is because portions were given earlier and the place to look for that is in the deed records. They are called Deeds of Gift and the language usually reads “ For Love and Affection....” or it could read for $1. It is understandable that one who has lived to an old age might parcel off his property, such as slaves and land, many years before his actual death. All that is left at time is to give the wife the homeplace for her lifetime, then to a son or daughter. Another reason why all children are not named is the children either died prematurely or moved off into another state and not kept in touch. The latter tends to so often be the situation because as the old family seat breaks up, the children disperse into other areas looking for better land. They obtain land grants and draw in lotteries so this is how we chase them down. The daughters' portions went to their husbands, so any names in the will or estate papers are suspect. I usually cross-check these names in marriage records.
Jeannette Holland Austin, author of over 100 genealogy books