Discount a product when purchased in combination with another product?

I'm wondering is it possible to discount a specific product when purchased in combination with another product?

For example, product A costs €10 on its own but if you purchase it along with Product D, Product A only costs €5.

Hoping someone can help 

2 hours ago, paul2009 said:

No, it is not possible on Squarespace.

Thanks Paul, hopefully this is something other Squarespace users would like and will get pushed out eventually. Thanks again for the help...

Yes, I would really like to see something like this! I would find it extremely helpful to offer this type of discount to customers! If you buy Product A the cost is $10, if you buy Product B the cost is $10, but if you buy Products A and B together the cost is $15.

Is there any type of code to make this possible, or would that be too complex?