How to add package weight to product weights

-- HikaShop version -- : 2.3.2

Hi, this is a question not a problem!

I want to update my manual shipping prices. I want to give each product a weight but then I want to add a "package weight" to the total order. To try to explain better here is an example:

Product A = 600g
Product B = 1000g
Packaging = 500g

1. customer buys ProductA so shipping weight = Product weight of 600g + packaging weight of 500g = 1.1kg in total
2. customer buys a multiple of ProductA x 3 so shipping weight = (600g x 3) + 500g = 2.3kg
3. customer buys ProductA + ProductB so shipping weight = (600g + 1000g) + 500g = 2.1kg

The packaging weight does not change even when I order more products.

If I set each product weight to be the actual weight plus the packaging then example 1. above would be correct at 1.1kg but examples 2 & 3 above would be wrong:
2. would become (600+500)x3 = 3.3kg
3. would become (600+500)+(1000+500)=2.6kg

Is this explanation clear? Do you know what I mean? Is it possible to do this?

Thanks
Niamh

Yes Nicolas, I do have all the different weight restrictions, and your method looks like it will work very nicely!
Thank you, it's great to have somebody more experienced to see all the possibilities