ForgedAnvil
Explorer
Also the only real issue I can see happening with the auto-calculation weight and container weight is that stuff like Bag of Holding, Portable Hole, Handy Haversack that can hole X amount of weight and still stay the same weight that they are it might cause a few bugs (ie items placed in Bag Of Holding are still being calculated in the weight when they shouldn't be). As far as I can think of right now there is no real way around that without VBA, Macros, and/or just clearing the cell that is containing the weight of said item after
it's added.
You could use a sumif in the weight cell for the Bag of Holding on the location and have that as a negative number then add the actual weight of the bag of holding. Something like, =-SUMIFS(ItemWeightsAbove,ItemLocationsAbove="Bag of Holding", ItemWeightsBelow,ItemLocationsBelow="Bag of Holding",)+WeightofBagofHolding)
You enter weights as normal for all items but Bag of Holding will end up a negative number to offset those items in the bag.