I am looking for a Substitute for dill

parsley (I like flat leaf much better than curly), mint

A combination of cilantro and mint would work nicely. Ottolenghi uses the two together in an excellent turkey burger recipe that I make often - and which I now also use in fish cakes. It would be delicious in both the beet chickpea cakes and the tzatsiki.

I add a touch of parsley, too, for good measure. ;o)

Any soft leaf herb your daughter likes.
Particularly good with the rest of the recipe - oregano or cilantro.

In the recipe head note the author suggests parsley or rosemary.