The One-Way ticket approach should work in airlines that offer that.
AA does not offer stop-over for domestic awards.
One stopover at NA gateway city on international award that involves North America. Note: NA is defined as geographic location not as in the award chart, for this purpose. Gateway is the First NA airport you enter NA or the Last NA airport you leave NA.
UA's one-way award only is offered on United's own metal.
BA has household account you can combine members' balances.
Most US airlines dont have this feature and as others mentioned above, you can "share" miles with a fee. Check respective airline's program on how much it would cost you.