Thanks. The is a chapter on mediation in this book: Book A Primer on Partial Least Squares Structural Equation Modeling
Also, you find some super useful articles on mediation that tackle this issue here: https://www.smartpls.com/documentation/literature/some-recommended-readings Just search the page for "mediation". For instance, the articles by Gabriel A Cepeda-Carrion , Christian Nitzl , and José L. Roldán are super useful! These authors, together with Cheah Jun Hwa and Siggi Siegfried Gudergan , have a new accepted paper on the topic, "A Primer on the Conditional Mediation Analysis in PLS-SEM", which they may share with you.