When it comes to finding synonyms for the phrase "in/into step," there are various options available. One could use the terms "in sync," "in harmony," "aligned," "matching," or "coordinated." All of these words imply a sense of unity and cooperation among different parties. Additionally, one could also use the phrase "on the same page" as a synonym for "in/into step." This phrase denotes a shared understanding and perspective. It is especially useful in situations where people need to work together towards a common goal. Ultimately, finding suitable synonyms for "in/into step" depends on the context in which they are being used.