Adding weft, over current install

I currently have my extensions installed with shr***ies and would like to know if I can install a row of weft up by my crown with protac using the last row of my current install as the place I would put it. Would it hurt anything or should I remove that row. I do not have enought hair up there to start another row for the weft, but i think there is enough space between the bond and my scalp to put the protac.

I've done this with almost every strand by strand install where I just couldn't get enough volume.  I would put a weft up near the top and at the very bottom.  I would connect the weft over the hair that was held by whatever strand by strand method I had.

I totally agree with metalgirl, it is probably a bad idea but it worked well for me and I would do it again.  For some reason it didn't feel like any additional weight.  I didn't have any problems, but now I think I'm sticking with wefts anway :)  I like the thickness you can achieve.