Dive into your creative stream
Am I the only one who thinks the ones saying these are Noelle and Dess?
[Image Description: Two screenshots from the video game Undertale, in the waterfall area. In the first screenshot, there are two echo flowers in the room, and Frisk is standing next to the left flower. The dialogue box shown at the bottom reads: "* C'mon, sis! * Make a wish!" In the second screenshot, Frisk is standing in the same room, next to the right flower. The dialogue box shown at the bottom reads: "* I wish my sister and I will see the real stars someday..."]
(Source: Screen-shoot by me, these echo flowers can be found in the wishing stars room, which is the 90th room or room_water6 in the game code).
I mean, we know that we freed the two sisters as well when we broke the barrier, if the Alarm Clock Winter Dialogues are anything to go by,
[Image Description: A dialogue box with Asgore's sprite on its left. The dialogue reads: "* His daughters get to grow up in the sunlight."] (Image source: https://undertale.com/alarmclock/asgore/) And echo flowers repeat the last thing that was said to them, no? So these wishes weren't said that long ago, therefore this theory could have some solid ground.