I am not sure what links you are referring to.
I am not sure what you mean by "real weight and hight [sic]". Do you mean the weight and height that the child would have if their lower limbs were present?
I think you could estimate weight from cadaver studies such as this one. You could search for references specific to children.
You could also use guidelines such as this one from the amputee coalition.
One way of getting height, often used in the eldery, would be to use a proxy such as armspan. A correction factor can be found by regressing height against arm-span and using the regression coefficients. You could do this using data collected in (e.g.) SMART surveys (you'll need to add armspan to the SMART dataset).
I assume that you want weight and height in order to calculate WHZ. If this is the case then you may want to use MUAC. This may, however, be elevated by addition muscle mass in the arms developed to overcome limitations imposed by the amputation.
I hope this is of some use.