You can use instances Variables,
Add an Instance Variable = "Weight" to the Objects to be carried
And then Add Two instance Variable to the Bags = "MaxWeight" & "CurrentWeight"
Nife = 20
Cooking Pot = 100
Helmet = 100
wardrobe = 50.000
Lets say that the Bag has already inside (Nife, Cooking Pot, Helmet) so
CurrentWeight = 220
BagMaxWeight = 300
Now say you wanna add another Item, in this case, the wardrobe as an example
on your Trigger to add the Items to the Bags first check or compare the "BagMaxWeight "
Bag: compare instance variable = "BagMaxWeight " is greater than
Bag.CurrentWeight + wardrobe.Weight ?
-If not you cant ad the object
-if yes then add the object to the Bag & add the object.Weight to the "Bag.CurrentWeight"
If you ever want to drop an Object
Remove the Weight of the object from the Bag
Bag subtract from "CurrentWeight" >>>>>>>>object.weight
If I didn't understand your question properly let me know