How can I adjust custom shipping rates for individual SKUs on my online store?

[IDS_Admin]

Our store is using custom rates for shipping.  For example, if you buy SKU#1 (which is large and heavy) it's $30, and if you buy SKU#2 (which is normally purchased as an add-on to SKU#2 and is smaller and lighter) it's only an incremental $4 for shipping.   We are naming the custom rate "standard" so that the rates are added together at check out.

Question 1:  While testing our approach, we noticed that if someone buys two units of SKU#1, the cost is $30 (not $60).  Is there a way to make the shipping cost $60 using custom shipping rates in this example?

Question 2: If someone buys SKU#2 alone without SKU#1 (which will be an edge case), we want to charge a different custom rate (e.g., $15) - to cover the shipping and fulfillment cost.  Is there a way to do this using custom rates?  Note: One idea is to create a new SKU that is "bundled" so someone can buy SKU#1 and SKU#2 as a bundle with a $34 shipping cost, but ideally we would like to keep each individual SKU as a separate SKU.

Thank you for your help and ideas.

[ToolifyStudio]

Are you using prices or weights as shipping rate conditions?

If you're looking for an easier way to deal with custom rates, checkout our app: https://apps.shopify.com/toolify-shipping