export the net as an fsh, now say the last net before the missing texture message appears is 13, once you have extracted the fsh change the name from t19__13.fsh to t19__14.fsh.
open dolffin & drag the t19__14.fsh into dolffin, click where its says nett, a distorted image of a net texture will appear, dont worry, its not corrupted.
next click on the paper clip looking icon, next to the yellow/blue x icon.
it will ask you to select the image to replace the current image.
select the net texture you want, dolffin will import that net texture, & create a .bak of the same fsh.
delete the .bak fsh & redrag the t19__14.fsh into dolffin & click on nett, you will see the texture has been replaced w/ 128x128 net texture.
now simply import w/ cm10 under net 14 & select the net for whatever stadium you choose.
do the same thing for all nets you want to import, next would be t19__15.fsh.
name the fsh to the next open net slot in cm10.