@Mike K.​  I have added a solution without using views.

temp_df = df2.join(df1, "colA", how = "left").select("*", df1.colB.alias("df1_colB")).drop(df1.colB)

df2 = temp_df.withColumn("colB", when((col("colB") <= col("df1_colB")) \
                                         & (temp_df.df1_colB.isNotNull()) \
                                         & (temp_df.colC == 'XYZ'), col("colB") + col("df1_colB")).otherwise(col("colB"))) \
                                        .drop("df1_colB")

Link to the full code in notebook w/ explanation:

https://github.com/bsthapit/Databricks_Solutions/blob/master/db_29380.ipynb