You could if you wish but since you have already added all that sugar the low-sugar pectin isn't necessary and any form of pectin could be used. The big advantage to using the lo-sugar pectin is that much less sugar than normal is required for it to set. And if you note the common used recipes for both apricot and plum jams they only call for 6 cups sugar to 2 quarts of fruit

In fact with a 1:1 ratio of fruit to sugar no pectin may be necessary if it is fully cooked to the gel point and you do the freezer plate test. Too much pectin at this point could result in an overly hard set.

Dave

Thanks for responding, Dave. What I read online was 5 cups of sugar to 2/1/2 cups of purée, which would be way too sweet. Also, this isn't just 6 cups of fruit chopped-up, but rather solid purée; I don't know if that makes a difference. Right now it's the consistency of a sauce. I just don't want to mess this up... too valuable. ;-)

I guess it all depends on which recipe you choose to follow. All sorts of them are floating around out there but I prefer to stick with the well-tested ones from NCHFP or Ball.

But if this is already a solid puree then I'd be hesitant to add further thickeners like pectin. I'd probably just process it and call it a fruit spread rather than a jam.

http://nchfp.uga.edu/how/can7_jam_jelly.html

Dave

Ah.... well... I decided on 'freezer something' since I didn't want to cook the fruit anymore. I boiled 1 pkg of regular pectin in 3/4 cup water and added to fruit/sugar mixture and jarred. This morning it is.... runny, and it will have to remain so. Into the freezer the jars go. It is sooooo delicious - Nectar of the Gods. ;-)