Cocktail recipe ideas for rose & elderflower sparkling lemonade.

in Austria we have this thing called Kaiser-Gespritzter, emperor’s spritzer, which is a regular white wine spritzer (equal parts wine and soda water, optional lemon slice) with a glug of elderflower syrup.
or, commonly known all over German-speaking countries as an alternative to Aperol spritz, the Hugo: prosecco (or other sparkling wine), a glug each elderflower syrup (or cordial, or lemon balm syrup) and soda water, and a sprig of fresh mint, poured over ice and stirred.
I could imagine both with the additional rose flavour, but maybe experiment with the ratios so it doesn’t get too sweet?
for something stronger I think it would be delicious to just substitute part of the tonic water in a gin & tonic by the lemonade …

sambuca has elderflowers already in it (small amount) and might play nicely off the lemonade with those flavors. likewise, pernod or arak.

Try testing a little Pimm's Cup No. 1 (gin with herbs) or just straight gin. Depending on how tart the lemonade is, you may need to add a little simple syrup.