Drawing a stability problem makes it easier to understand
When working with a stability sum use the KG's for the vessels displacement and the weight that's being loaded/discharged or shifted, forget the weights at the moment
Draw a big "E" as follows and insert 4 dots.
Name the bottom dot "K"
Name the middle dot "G"
Name the top dot "M"
Find if the weight being loaded/discharged is bigger than the vessels own KG or below it, if its bigger then put g1 above the vessels own KG, if less than the vessels KG, then put g1 below the vessels KG

From the Keel lay off the distance for the vessels displacement (KG)
From the Keel lay off the distance for the weight loaded/discharged (Kg)
Subtract (KG from Kg1) this gives small "d"
If the weight is a shifted weight subtract where the weight was and where it is now (Kg1 - Kg2) = "d"

Using the formula:- Gg1 = w x d = W d (+ if loaded, - if discharged) (only use W if a shifted weight) (don't use small d for shifted weight)
If using more than one weight, best to do a Table of moments

Remember these Formulas they are important

KG = KM - GM
GM = KM - KG
KM = KG + GM

Always add F.S.E. to KG or Subtract it from GM