Well one of the first times I got to invited to a baby shower I was suprised that they had alcohol, I mean pregnant women right?
But then I saw that they had an extensive selection of non alcoholic sparkling juices and mocktails. Which turns out is actually a thing that seems to be common at baby showers, at least that is what I learned on the Baby Cottage.
Some of the selections were nice and I actually don't drink so I was willing to give them all a go. This was actually where I also learned about San Pellegrino.
There were the classics. Ginger is good. It sounds like she is a fan of citrus which will make this way easier.
Look into different types of lemon/limeades and start playing around with different flavors. Add in some herbs and other fruits. Try to go fresh squeezed if possible. Think blueberry thyme limeade or strawberry ginger lemonade.
A great deal of the enjoyment people get from cocktails is the idea of the work and care that goes into them.
Fresh juice, fresh herbs. Using different types of sweeteners are good too, demura, agave, honey.
I really enjoyed the ghetto mocktail. I mixed 50/50 Orange and Pineapple juice and a splash of grenadine. Sometimes you've got to get fruity.
Still non-alcoholic cocktails can really suck if they end up just being fruit juice and flavored syrups. Back in college I had a boyfriend that would mix me things that made me want to puke.
A good way to avoid that is to infuse your ingredients with other flavors, which will give depth to what is essentially juice, sugar and perhaps citrus.
We use a whole bunch of infusions at my bar; apple juice works really well, we use cardamom-apple and curry leaf apple in various drinks. They're made by literally dropping the fresh ingredients into a bottle of apple juice and letting it rest for 24h.
You should also consider making your own syrups. Simple syrup is made dissolving 2 parts (Demerara, trust me) sugar into 1 part water. But throw in there some star anise or some cinnamon and all of a sudden there's another element to your non-alcoholic cocktails. Tea syrups also work incredibly well, green tea and earl grey particularly.