After finding that I was retaining about 2 inches a year I decided to employ the use of individual plaits on my natural hair to retain length. I don't know if this will help you since you're relaxed, Tiffers, but I will put it out there anyway.
I do not add any extra hair, I use my hair only. Since it seems I can retain almost NO hair, when I let it loose, I take down the first two or three rows around my edges one plait at a time, combing/brushing out the shed hair and any lint, moisturizing and sealing, and replaiting about every other week and fix the rest every 6 weeks. I will only let my hair loose four times a year, for trims.
Sometimes I call this method pseudo-locing, because I style it like its locs.
I cowash everyday, spray with Aphogee K> and Haw. Silky 14-n-1 then add a creamy leave-in and style. I clean them, deep condition them, and I am going to try my powder-pastes on them and see how it works.
My sister, who is a BSL natural uses this method to give her hair a rest from her hard presses, and her buns and pinups look beautiful because they resemble micros. She only wears hers randomly, 4 to 6 weeks at a time, but they still help.
I don't know if this regimen is appealing to anyone, but if the concept is helpful in any way, then great.