We have a whole-house softener and I would not dream of life without it. If you don't have any softening, getting a dishwasher with that capability would be a no-brainer.

Another whole house water softener here. Have had my F&P DDs in this house for 8 years --- had a set in my last house for the 3 years I lived there.

When you have whole-house water softener, you don't need to do anything special. Be sure to follow the directions on detergent and amount of detergent to use. In my models, I use Cascade powder (always use powder) and I carefully measure a scant teaspoon into each cup.

The directions will tell you what kind of detergent and how much, so rely on them.

I have a whole house water softener too. Love my dds.

I use 2 tsp and 1 tsp of powdered dw detergent with enzymes. Usually a store brand.

I keep my soap in a sugar dispenser which makes it easy to pour into the soap holders of the dw.

Putting in the whole house softener (with r/o drinking water faucet) was one of our better decisions so I can't comment on the softener.
But we do love the convenience, loading and cleaning ability of our DDs.
They use a minuscule amount of detergent. I've been using cascade.

Well, for up to 6 grains hardness, the FP user manual says to set the softener on setting "0", which I am guessing means "off". I don't think that the FP senses that actual hardness (like maybe some Miele models do) and adjusts, you just set it on 0 to 5 and it varies the amount of softening. Its only with hardness above 14.6 grains/gallon that they "require" softening (external or internal).

So, there's a good chance that I will find "0" to be my best setting anyway. There is also a good chance that my wife will accidentally put rinse aid in the salt reservoir, which will kill the softener...