wiy +1 on the long post
purple- i gotta agree with everyone here. Segulos are not like taking a week’s prescription to get rid of strep. Its an added zchus. Don’t say perek shira with the sole intend of your sister getting engaged. That can also lead you into a trap of writing it off, disappointment, etc. In the right time, she will find her zivug, b’ezras Hashem. It may be tomorrow, it may be in 10 yrs. We cannot know. Yes, Hashem hears your tefillos and He answers. But the answer may be ‘not yet’, and the zchus may go for something else, someone else… If you want an encouragement for this, you can look at it as perhaps for your 40 day cycle, she now has to date 1 less wrong boy.