This has been discussed before here, extensively. It is not recommended, because you have no way of knowing whether the dry constituents of the powder are evenly distributed throughout the powder packets. Plus, keeping the powder dry once you've opened the factory-sealed pouches is tough to do. This is how the original 1-L packages of Xtol came to grief--poor packaging.
Others have had success mixing the developer double-strength (ie, 2.5L solution) and storing in completely full GLASS bottles. You can properly dilute it upon use. It should last 6 months in this fashion, and some have reported far greater longevity. Besides, it's so cheap, who cares?
If your family's objection to your using the fridge is safety rather than space limitations, you should educate them better. Xtol is quite harmless, as are most photographic chems. There's no reason that properly marked chemical bottles need be disturbed by family members old enough to read. Not sure if refrigeration makes any real difference, however.