Would Like To Have An Extra Inch Of Length Added To The Current Unit.

[lvlace]

Adding to the front or back is feasible. I've done it many times with my pieces during the last 10+ years. My additions have been lace to lace only. Not difficult to do on the back. A bit more difficult on the front since the front hairline will be visible.

As for adding poly I suspect the only feasible way is to cut down an existing poly hair piece then adding the "wedge" to the poly piece in need of an addition. I have been ventilating for over 10 years. I have never tried to ventilate poly.Trying to ventilate to a fragile piece of poly would be quite a trick. The poly would likely tear when the knot it tightened. More feasible to use lace.
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Companies......call Eric at Northwest Lace, John at Toplace, or Debbie at Splitends...http://splitendshairreplacement.com/index.html.