You know I always thought that Miku should be the least likely to be Lolikano and Yotsuba the most likely.
After this chapter I'm not so sure anymore because of one fact.
Ichika tried to disguise as Miku with the plan to pose as Lolikano.
Why? What's the benefit? Why not pose as Ichika or disguise as another sister?
Could be of course because she planned to deny Miku's love as Miku.
But I think you should consider the possibility that Miku is in fact Lolikano. Then it makes sense to impersonate her if Fuutarou remembers something. Only by dressing as Miku would anyone be able to cancel any affection Fuutarou had from the past.
Still just a theory but as good as the others.