Thicken and put fillet on complex surfaces

Hello guys,

Here is simply a chair I have copied from a tutorial. the problem is that i can't put variable fillet on the edge1 and not even able to thicken the chair. I tried to thicken the part before applying the knit command, didnt work, tried to select check boxes (solid and Merge) in the knit command as well, did not work... I litteraly need hints from experts.

thank you in advance

SolidworksSurfacing