The GE links would work as repeaters but they are terrible for that purpose as they have a firmware bug (this is the reason they are not on the official “works with SmartThings” compatibility list) which causes them to lose touch with the network from time to time. This has nothing to do with SmartThings it’s also why you will see discussions elsewhere from people who have a Hue bridge about the GE’s showing up with a yellow ! So I cannot recommend them as repeaters.
Instead, you can use the similarly priced hue whites connected directly to the smart things hub or the Cree. Or the Osram lightify if you like being able to change the color temperature.
The only thing about using the Hues connected directly is that there is no way to reset them to factory specifications unless you also buy a separate device, the lutron connected bulb remote. It costs about $30 at Home Depot, but you only need one no matter how many bulbs you have. Even though it’s a different brand then the Hues, it just happens to have the exact command you need to reset them after they’ve been connected to SmartThings, which the similar Phillips hue dimmer switch does not. Also, you need a different device handler if the Hues are connected directly. (Other brands of bulbs will not require this device if they use a “blank” method to factory reset the individual bulb. The Hues don’t use a blink method, which is why an additional device is required. But they are excellent bulbs, very well engineered, and now that the price is typically $15 US at Best Buy, certainly worth considering.)
Anyway, the main point is don’t count on the GE links as repeaters. But there are other bulbs that you can consider.
I agree that the iris smart plug is the simplest solution since it repeats both Zigbee and Z wave. Tell your Atlanta relatives to bring an extra suitcase.