The answer to what can be done by cloud seeding is at best still incomplete and inconclusive. More study is needed on the fundamentals of how rain falls and how cloud seeding might modify this. But here's a report on this controversial subject in the light of the information now known.
Shaw, R. H.
"Situation Report on Cloud Seeding,"
Iowa Farm Science: Vol. 11
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol11/iss9/2