Sorry, this should be straightforward but I can't figure it out even after trying and using the manual. I was able to collapse the data I asked about before but I made a mistake for one country that has two different values in the data set (and the one I want to merge with it). Italy is Italy/Sardinia for observation number 90 and Italy for observation 206. I need to replace the observations with a score of 0 in observation 90 with the values of the variables for observation 216. I tried a replace in a loop that included:
replace gwno1901[_216] if *[_90]==0

but got:

weights not allowed