The multisize table minimum and maximum size picklist currently reflects men's minimum and maximum chest circumference in centimeters, taken from the Russian men's standard size charts.
A redesign of the multisize system is needed to enable each table to contain it's own maximum and minimum size, and so that we don't have to maintain a global list. This redesign will enable sizes like Small, Medium, Large, and children's sizes like 0 to 6 weeks or husky sizes 24H, basically a redesign will enable all sizes which aren't based on men's chest circumference!
For now, the workaround is to create an individual measurement file for each size that you wish to use.
By the way, if you would like to contribute towards this fix, we accept donations on our website at http://valentina-project.org. Every donation gets us closer to fixing issues such as these.