Originally Posted by oldmate
Jasperrrr, no, whatever sugar you add back into solution after your primary fermentation will cause another fermentation regardless of how slow you add it in. If you don't mind still ciders then you can always stabilise with sorbate and metabisulphite, or as others have said pasteurise. There is of course an in-between which is finding the sugar concentration of the concentrate and adjusting your addition to bottle carb, similar to carbing with sugar.
I thought he said previously that he had already stabilized, and adding it slowly will let flavors meld , if you add it all the concentrate at once an taste, 3 days later it won't taste the same IMO and experience, which is little haha