Aaahhh, ya gotta love the oil business. I have soo many friends who live similarly. That's so nice you are thinking of her stepkids as well.
Whenever I don't know what to get someone, books are always my default gift. Easy to wrap and send esp with the book rate postage. There are tons of great books on sale for the holidays. Check out national awards lists like Caldecott, Texas Bluebonnet, Texas 2x2 and Scholastic to help narrow your search. Invest in their future through reading! :)
What's your budget?
Fishing poles
Magic or science set
Magnifying glasses or microscope for kids
Binoculars
Board or card games (they are all on sale right now anywhere you go)
Magazine subscriptions
Discovery Kids has a great line of outdoor toys - bug collecting, star gazing, etc.
gl!